Elastomeric film-forming compositions and articles made from the elastomeric film

ABSTRACT

The invention relates to an elastomeric film-forming composition comprising a carboxylic acid- or ester-grafted polychlorobutadiene, and one or more cross-linking agents. The invention also relates to dipped articles, gloves, methods of manufacture and uses involving the composition.

FIELD

The present invention relates to elastomeric film-forming compositionsfor use in manufacturing dipped articles, such as gloves, and methodsfor forming elastomeric films and gloves.

BACKGROUND OF THE INVENTION

Whenever a thin film glove is worn for barrier protection either bymedical personnel or for industrial purposes the gloves will becomeuncomfortable to the wearer after a short time. This is due to thefatigue associated with the resistance of the glove caused by anintrinsic character known as “lesser elasticity”, which is measured interms of its modulus. A higher modulus glove material is lesssatisfactory for such gloves.

Gloves that are made from natural (polyisoprene) rubber have favorablefeel and comfort properties. However, natural (polyisoprene) rubber isassociated with potential allergen (which causes Type I allergy). Inview of this allergenic property, natural (polyisoprene) rubber isgenerally not suitable for use in the manufacture of dipped articles,such as rubber gloves due to the adverse effect of natural(polyisoprene) rubber on the wearer.

The current trend is to use synthetic materials like nitrile rubber,polyisoprene, styrene butadiene rubber, butyl rubber and vinyl toproduce dipped articles such as gloves. Over the past few years thevolume of glove production using synthetic materials has increasedsubstantially. However, nitrile rubber, styrene butadiene rubber, butylrubber and vinyl are not able to provide the favorable feel and comfortof natural (polyisoprene) rubber. While synthetic polyisoprene canprovide a favorable feel and comfort that is comparable to that ofnatural (polyisoprene) rubber, synthetic polyisoprene is very expensiveand is not suitable for use in the manufacture of some articles such asthin film gloves, which are used in high volumes and discarded.

Polychloroprene is a synthetic material that has been found to exhibit asimilar texture, feel and softness as natural polyisoprene.Polychloroprene differs from natural polyisoprene in that the methylgroup at the 2-position of the isoprene monomer is replaced withchlorine. However, conventional polychloroprene is very expensive andprocessing of polychloroprene requires a high energy input. In additionto these problems, a higher film thickness and high level of curingchemicals (almost 3-4 times that of natural polyisoprene) is required.For at least these reasons, conventional polychloroprene is notpreferred for use in the manufacture of some articles, such as rubbergloves and particularly gloves that are discarded after a single use.

Elastomeric compositions such as those described above have thepotential for application in articles other than gloves. For example,dipped articles may be configured for use in medical applications suchas surgical gloves, examination gloves, catheters, tubing, protectivecovering, balloons for catheters, condoms and like, or for use innon-medical applications, such as industrial gloves, laboratory gloves,household gloves, gardening gloves, electrical gloves, irradiationgloves, finger cots, weather balloons, clean room gloves for electronicindustries, gloves for food contact and food processing and biotechnicalapplications and the like. New developments in this field may identifyfurther applications for these types of dipped articles that have notyet been identified.

There is a therefore a need for alternative or improved dipped articles,including compositions for forming these articles and methods ofmanufacturing the articles.

SUMMARY

The present inventors have found that the selection of a carboxylicacid- or ester-grafted polychlorobutadiene as a component of anelastomeric film-forming composition can be used to prepare dippedarticles, such as gloves, which have improved properties. Thecomposition of the invention can be used to prepare very thin layers ofelastomeric film using a minimal amount of polymeric material whilestill maintaining suitable properties such as elasticity, strength,durability and the absence of defects like pin holes or weak spots.

In one embodiment, there is provided an elastomeric film-formingcomposition comprising: (a) a carboxylic acid- or ester-graftedpolychlorobutadiene, and (b) one or more cross-linking agents. Theelastomeric film-forming composition of the present invention is not asimple physical blend of polychloroprene with other synthetic material.Instead, the elastomeric film-forming composition contains a polymerthat is a carboxylic acid- or ester-grafted polychlorobutadiene. Inother words, the elastomeric film-forming composition of the presentinvention comprises a single polymer consisting of chlorobutadiene unitsto which one or more carboxylic acid residues or esters thereof aregrafted. In these polymers the carboxylic acid residues are covalentlyattached to the chlorobutadiene units as substituents on thepolychlorobutadiene. In some embodiments, there are no carboxylic acidgroups in the main chain of the polymer. In some cases, minor changes tothe structure of a polymer may have a significant effect on theproperties of elastomeric films or dipped articles produced using thepolymer. In one embodiment, the elastomeric film-forming composition ofthe invention can be used to form thinner layers of elastomeric film. Inanother embodiment, the elastomeric film-forming composition of theinvention can be used to prepare dipped articles, such as gloves, whichmay have improved properties such as improved feel, improved softness orincreased elasticity.

Using a carboxylic acid- or ester-grafted polychlorobutadiene providesadvantages when compared to the use of a blend of, for example, apolychloroprene and a polymer of carboxylic acid containing monomers.For example, dipped articles prepared from the elastomeric film-formingcomposition of the invention may possess improved physical properties.In some embodiments, the dipped articles prepared from the elastomericfilm-forming composition of the invention have a higher tensile value atbreak, a lower modulus at 300% and/or a lower modulus at 500% and/or ahigher elongation to break when compared to elastomeric filmcompositions containing blends of polychloroprene and a polymer ofcarboxylic acid containing monomers. In some embodiments, the dippedarticles prepared from the elastomeric film-forming composition of theinvention have a tensile strength of greater than or equal to about 2000psi, a modulus at 300% of about 100 to 2000 psi, a stress at 500% ofabout 200 to 3000 psi, and/or an elongation to break of about 400 to1500%. Preferably, the dipped articles prepared from the elastomericfilm-forming composition of the invention have a tensile value at breakof greater than 2100 psi, a modulus at 300% of less than 660 psi and/ora modulus at 500% of less than about 2400 psi and more preferably lessthan about 1015 psi and/or an elongation to break of greater than 520%,and preferably greater than 650%. In some embodiments, the improvementsmay be even better when using the combination of one or morecross-linking agents, such as a combination of an ionic cross-linkingagent (for example a metal oxide or a metal hydroxide) and a covalentcross-linking agent (for example sulphur or a sulphur-containingvulcanising agent). In other embodiments, the improvements may be evenbetter when using a carboxylic acid- or ester-graftedpolychlorobutadiene having a selected degree of carboxylation.

In another embodiment, there is provided an elastomeric film comprisingat least one layer of a cured composition comprising a carboxylic acid-or ester-grafted polychlorobutadiene, and one or more cross-linkingagents. The elastomeric film may be made from an elastomericfilm-forming composition according to any of the embodiments of thecomposition described herein. The elastomeric film may be in the form ofa dipped article, where a former in the shape of an article is dippedinto the elastomeric film-forming composition and the composition iscured on the former.

In yet another embodiment, there is provided a dipped article made froman elastomeric film comprising at least one layer of a cured compositioncomprising a carboxylic acid or ester-grafted polychlorobutadiene, andone or more cross-linking agents. The dipped article may be made from anelastomeric film-forming composition according to any of the embodimentsof the composition described herein.

Dipped articles, such as gloves made using the composition of thepresent invention have been found to possess favourable characteristicssuch as favourable feel and comfort, improved softness and can be madefrom very thin layers of elastomeric film without increasing thepresence of defects such as pin holes, weak spots or other defects.Elastomeric film-forming compositions that can be used to form very thinlayers of elastomeric film without compromising the elasticity,strength, durability or other characteristics such as feel, comfort,softness or the absence of defects, allows the film to be suitable foruse in specific applications such as, for example, in medicalexamination gloves and surgical gloves, where it is important that thefilm does not prevent the wearer from having good tactile perception.

In yet another embodiment, there is provided a glove comprising at leastone layer of elastomeric film comprising a carboxylic acid orester-grafted polychlorobutadiene, and one or more cross-linking agents.The glove may be made from an elastomeric film-forming compositionaccording to any of the embodiments of the composition described herein.

The present inventors have identified that a polymer comprising acarboxylic acid- or ester-grafted polychlorobutadiene can be used toprepare dipped articles having improved properties. The dipped articlesprepared from the elastomeric film-forming composition of the inventionretain the favourable feel and comfort that is closer to natural rubberfilm yet is free of proteins and other potential allergens (causing TypeI allergy) associated with natural rubber. Where the dipped article is aglove, retaining the properties of natural rubber gloves also means thatthe products are easily donnable without any visible powder anti tackmaterial. In addition, the dipped articles prepared from the elastomericfilm-forming composition of the invention also possess improved physicalproperties. In some embodiments, the dipped articles prepared from theelastomeric film-forming composition of the invention have a highertensile strength, a lower modulus at 300%, a lower modulus at 500%and/or a higher elongation to break when compared to other elastomericfilms used to form dipped articles or gloves. In some embodiments, thedipped articles prepared from the elastomeric film-forming compositionof the invention have a tensile strength of greater than or equal toabout 2000 psi, a modulus at 300% of about 100 to 2000 psi, a stress at500% of about 200 to 3000 psi, and/or an elongation to break of about400 to 1500%. For example, the elastomeric film prepared from thecomposition of the present invention has a tensile strength of at leastabout 2100 psi, a modulus at 300% of less than 660 psi, a stress at 500%of less than about 2400 psi and more preferably less than about 1015psi, and/or an elongation to break of greater than 520% and preferablygreater than about 650%. This improvement may be even better when usingselected cross-linking agents or when using an elastomeric film-formingcomposition that contains a carboxylic acid- or ester-graftedpolychlorobutadiene in which the carboxylic acid group or ester group ispresent in a selected amount.

In some embodiments, the combination of an ionic cross-linking agent(for example a metal oxide or a metal hydroxide) and a covalentcross-linking agent (for example sulphur or a sulphur-containingvulcanising agent) as the cross-linking agents with a carboxylic acid-or ester-grafted polychlorobutadiene provides an elastomeric film havingimproved properties. In other embodiments, the cross-linking agent maybe selected from, but not restricted to accelerators (including thecarbamates such as thiocarbamates (e.g. zinc dibutyl dithiocarbamate(ZDBC), zinc diethyl dithiocarbamate (ZDEC)), thiurams (e.g.tetraethylthiuram disulfide (TETD), tetramethylthiuram disulphide(TMTD)), thiourea (Ethyl thiourea (ETU) and diphenylthiourea (DPTU)),thiazoles (e.g. mercapto benzothiazoles (MBT), mercapto benzothiozoledisulphide (MBTS), zinc 2-mercaptobenzothiazole (ZMBT)), guanidines (eg.Diphenylguanidine (DPG)) and aldehyde/amine-based accelerators (e.g.hexamethylenetetramine)); ionic cross-linking agents including organicand inorganic metal oxides, organic and inorganic metal hydroxides andorganic and inorganic peroxides (including the multivalent metal oxidecross-linking agents, such as lead oxide, magnesium oxide, barium oxide,zinc oxide, manganese oxide, copper oxide, nickel oxide, aluminiumoxide, barium hydroxide, manganese hydroxide, copper hydroxide, nickelhydroxide, aluminium hydroxide,1,1-di(t-butylperoxy)-3,3,5-trimethylcyclohexane and combinationsthereof); cross-linking monomers; reactive oligomers; polyisocyanateoligomers; functional, cross-linkable polymers; derivatives of ethyleneglycol di(meth)acrylate (such as ethylene glycol diacrylate, di(ethyleneglycol) diacrylate, tetra(methylene/ethylene glycol) diacrylate,ethylene glycol dimethacrylate (EDMA), di(ethylene glycol)dimethacrylate (DEDMA), tri(methylene/ethylene glycol) dimethacrylate,tetraethylene glycol dimethacrylate (TEDMA)); derivatives ofmethylenebisacrylamide (such as N,N.-methylenebisacrylamide,N,N.-methylenebisacrylamide, N,N.-(1,2 dihydroxyethylene)bisacrylamide);formaldehyde-free crosslinking agents (such asN-(1-Hydroxy-2,2-dimethoxyethyl)acrylamide); divinylbenzene;divinylether; diallyl phthalate; divinylsulfone and the like. In oneembodiment, the cross-linking agent comprises a metal oxide or a metalhydroxide and sulphur or a sulphur-containing vulcanising agent.

In some embodiments, the elastomeric film-forming composition of theinvention contains a carboxylic acid- or ester-graftedpolychlorobutadiene in which the carboxylic acid group or ester group ispresent in an amount of from 0.01% to 8% by weight of chlorobutadieneunits present in the polymer. Using a carboxylic acid- or ester-graftedpolychlorobutadiene having this amount of carboxylic acid or estergroups provides an elastomeric film having improved properties.

Polychloroprene differs from natural polyisoprene in that the methylgroup at the 2-position of the isoprene monomer is replaced withchlorine. Polychloroprene exhibits a similar texture, feel and softnessas natural polyisoprene, but as described above in relation to naturalpolyisoprene, polychloroprene is very expensive and is not preferred foruse in the manufacture of articles such as rubber gloves, andparticularly gloves that are discarded after a single use. In addition,the processing of polychloroprene requires a high energy input, a higherfilm thickness and high level of curing chemicals (almost 3-4 times thatof natural polyisoprene). For at least these reasons, polychloroprene isnot preferred for use in the manufacture of some articles.

Using a carboxylic acid- or ester-grafted polychlorobutadiene providesadvantages when compared to the use of polychloroprene alone. As oneexample, if a composition of polychloroprene alone is used to preparegloves that satisfy industry requirements, the gloves generally need tobe thicker and require a greater amount of polymeric material to be usedper glove. One disadvantage of thicker gloves can be seen in surgicalgloves and medical examination gloves, where thicker gloves reducesensitivity for the wearer. Accordingly, a balance must be struck inorder to produce an elastomeric film having an appropriate thickness,using a minimal amount of polymeric material and in satisfying industryrequirements for the specific application that the resulting article isto be used. The present inventors have found that gloves or otherarticles prepared from the elastomeric film-forming composition of theinvention possess excellent characteristics or properties such asfavourable feel and comfort, and improved softness. Gloves or otherarticles prepared from the elastomeric film-forming composition of theinvention can be made from very thin layers of elastomeric film andusing a minimal amount of polymeric material while still maintainingindustry requirements for the specific applications such as elasticity,strength, durability and the absence of defects like pin holes or weakspots. The use of less polymeric material also means that the productcan be produced at a lower cost.

The present inventors have also identified that the elastomericfilm-forming composition allows for simple processing with considerablesavings in the required energy input, in the material of constructionand in the chemical consumption for production of articles with thecomposition of the invention. Articles produced using this compositioncan be produced at lower cost and can be manufactured with fewerprocessing hurdles, without compromising the benefits provided using apolychloroprene (for example, the favorable feel and comfort).Therefore, the resulting articles may provide the favorable propertiesof natural rubber latex, such as comfort for the wearer where thearticle is for example a glove, and avoids the problem of Type I allergyassociated with natural rubber latex. In some embodiments, the amount ofchemicals and materials used in the preparation of dipped articles maybe reduced when the elastomeric film-forming composition of theinvention is used. In some embodiments, the amount of cross-linkingagents such as zinc oxide that is used in the elastomeric film-formingcomposition of the invention may be reduced by up to 50% when comparedwith other compositions. The reduction in the amount of chemicals andmaterials used may produce dipped articles having improved propertiesand may also minimise manufacturing costs. In some embodiments, aminimal amount of polymeric material and/or a reduced amount ofchemicals and materials may be used to make elastomeric films whilemaintaining the necessary industry requirements for certain applicationssuch as elasticity, strength, durability and the absence of defects likepin holes or weak spots. The use of less polymeric material also meansthat the product can be produced at a lower cost.

In a further embodiment, there is provided a method of manufacturing anelastomeric film comprising the steps of: (i) dipping a former into acomposition as described above to produce a layer of elastomericfilm-forming composition on the former, and (ii) drying and curing theelastomeric film-forming composition.

In one embodiment, the method will further comprise, prior to step (i),the steps of: (a) dipping the former into a coagulant, followed by (b)drying or partially drying the coagulant-dipped former.

In another embodiment, the method will further comprise, following step(ii), the steps of:

-   -   (iii) dipping the former into a composition as described above        to produce a further layer of elastomeric film-forming        composition on the former,    -   (iv) optionally repeating the drying step (ii) and the further        dipping step (iii), and    -   (v) drying and curing the layered elastomeric film.

In some embodiments, the drying step and the dipping step are repeatedto produce a film having from 2 to 15 layers. For example, a method forproducing a film having two layers will require that the drying step andthe further dipping step are repeated at least once.

In a still further embodiment, there is provided a multiple-coatingmethod of manufacturing a layered elastomeric film comprising the stepsof:

-   -   (i) dipping a former into a composition as described above to        produce a layer of elastomeric film-forming composition on the        former,    -   (ii) drying or partially drying the elastomeric film-forming        composition,    -   (iii) dipping the former into a composition as described above        to produce a further layer of elastomeric film-forming        composition on the former,    -   (iv) optionally repeating the drying step (ii) and the further        dipping step (iii), and    -   (v) drying and curing the layered elastomeric film.

In a still further embodiment, there is provided an elastomeric filmproduced by the method as described above. The elastomeric film producedby the method as described above may involve the elastomericfilm-forming composition according to any of the embodiments of thecomposition described herein.

In a still further embodiment, there is provided the use of anelastomeric film-forming composition comprising a carboxylic acid- orester-grafted polychlorobutadiene, and one or more cross-linking agents,in the manufacture of a glove. The use may involve the elastomericfilm-forming composition according to any of the embodiments of thecomposition described herein.

Additional details concerning the dipped articles, their properties andtheir manufacture are described in further detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the present invention will now be furtherdescribed and illustrated, by way of example only, with reference to theaccompanying drawing in which:

FIG. 1 is a graph showing the experimental results obtained for theelastomeric films obtained from the compositions of Examples 1 to 10.The left hand axis shows the values obtained in psi for the tensilestrength, the modulus at 300% and the modulus at 500%, while the righthand axis shows the values obtained in % for the elongation to break.Examples 1 and 2 used a composition containing a carboxylic acid-graftedpolychloroprene having a carboxylation level of 1.5 and 2.5%,respectively, without blending with a second elastomer. Examples 3, 4, 5and 6 used a composition containing nitrile butadiene rubber as a secondelastomer in an amount of 15 phr. Examples 3 and 4 used compositionscontaining the same amount of cross-linking agents (5 phr ZnO, 1 phrsulphur and 1 phr ZDBC), while Examples 5 and 6 used compositionscontaining a lower amount of cross-linking agents (2.5 phr ZnO, 0.5 phrsulphur and 0.5 phr ZDBC). Examples 3 and 5 used a compositioncontaining a carboxylic acid-grafted polychloroprene having acarboxylation level of 1.5%, while Examples 4 and 6 used a compositioncontaining a carboxylic acid-grafted polychloroprene having acarboxylation level of 2.5%. Examples 9, 8, 7 and 10 used a compositioncontaining nitrile butadiene rubber as a second elastomer in an amountof 30%, 45%, 75% and 95% by weight of the polymer component of thecomposition on a dry basis. Examples 9, 8, 7 and 10 used a compositioncontaining a carboxylic acid-grafted polychloroprene having acarboxylation level of 0.01%. The amount of ZnO used in the compositionof Examples 9, 8, 7 and 10 was 4 phr, 3 phr, 2 phr and 1.2 phr,respectively. The amount of sulphur used in the composition of Examples9, 8, 7 and 10 was 1.5 phr. The amount of ZDBC used in the compositionof Examples 9, 8, 7 and 10 was 1.5 phr, 1.25 phr, 1.0 phr and 0.8 phr,respectively.

DETAILED DESCRIPTION

The elastomeric film-forming composition, dipped articles, gloves,methods of manufacture and uses thereof, according to particularembodiments of the invention are described below.

The present invention relates, in particular, to compositions containinga carboxylic acid- or ester-grafted polychlorobutadiene, and to dippedarticles, such as gloves or other products, which are made from thecomposition. It will be appreciated that the composition of theinvention could be modified, such as by the addition of additives or byaltering the relative amounts of other components, to suit the purposeof the dipped article or glove made from the composition.

Elastomeric Film-Forming Composition

The elastomeric film-forming composition comprises a dispersion oremulsion of a polymer containing chlorobutadiene units and one or morecarboxylic acid residues or esters thereof in a liquid. The compositiongenerally comprises the polymer as well as cross-linking agents in theliquid medium.

The liquid medium is typically water, although other solvents such asalcohols (including aliphatic alcohols and aromatic alcohols) oraromatic solvents may be used. Examples of suitable solvents includewater, methanol, ethanol, n-propanol, isopropanol, n-butanol,butanediol, diethanolamine, butoxyethanol, ethylene glycol, glycerol,methyldiethanolamine, propanediol, pentanediol, propylene glycol,triethylene glycol, furfural alcohol, benzyl alcohol, benzene, toluene,xylene, pyridine, tetrahydrofuran, benzonitrile, chlorobenzene and1,2-dichlorobenzene. Preferably, the solvent used is water. When wateris used, the polymer is in colloidal form and processing and handlingare simplified.

A solvent, or preferably water, is added as a diluent in an amount toreach the required total solids content of the total composition, or therequired total solids content of the polymer component of theelastomeric film-forming composition. In one embodiment, the solventcomprises from 40 to 95% by weight of the total composition. In anotherembodiment, the composition contains water in an amount of from 40 to95% by weight of the total composition. Other optional components, asdescribed in further detail below, may also be present in thecomposition.

The total solids content of the polymer component of the elastomericfilm-forming composition is from 5% to 60% by weight of the composition.The polymer component of the elastomeric film-forming compositionincludes the amount of the carboxylic acid- or ester-graftedpolychlorobutadiene and, where present, the amount of the secondelastomer. The percentage of total solids content (TSC %) can varywithin this range. Preferably, the total solids content of the polymercomponent of the elastomeric film-forming composition is about 5 to 55%,10 to 60%, 10 to 55%, 15% to 60%, 15% to 55%, 20% to 60%, 20% to 55%, 5%to 50%, 10% to 50%, 20% to 50%, 30% to 60%, 30% to 55%, 30% to 50%, 35%to 60%, 35% to 50%, 40% to 60%, 40% to 55%, 40% to 50%, 45% to 60%, 45%to 55% or 45% to 50%.

The polymer component plus the other components of the elastomericfilm-forming composition are diluted with a liquid medium (such aswater) to reach the desired concentration. The total solids content ofthe elastomeric film-forming composition is from 5% to 60% by weight ofthe composition. The percentage of total solids content (TSC %) can varywithin this range. Preferably, the total solids content of theelastomeric film-forming composition is about 5 to 55%, 10 to 60%, 10 to55%, 15% to 60%, 15% to 55%, 20% to 60%, 20% to 55%, 5 to 50%, 10% to50%, 20% to 50%, 30% to 60%, 30% to 55%, 30% to 50%, 35% to 60%, 35% to50%, 40% to 60%, 40% to 55%, 40% to 50%, 45% to 60%, 45% to 55% or 45%to 50%.

Generally, for forming a thin or disposable type of glove such as asurgical glove or medical examination type glove, the total solidscontent will be towards the lower end of this range. For example, thetotal solids content may be within one of the following ranges: 5 to50%, 10 to 50%, 5 to 40%, 10 to 40%, 5 to 35%, 10 to 35%, 5% to 30%, to30%, 5% to 25%, 10 to 25%, 5% to 20%, 10 to 20%, 15% to 50%, 15% to 40%,15% to 35%, 15% to 30%, 15% to 25%, 15% to 20%, 20% to 50%, 20% to 40%,20% to 35%, 20% to 30%, 20% to 25%, 25% to 35%, 35% to 40% or 35%-50%.For forming thicker gloves such as household gloves or industrialgloves, the total solids content will tend to be higher or the glovewill be produced from many more layers. Thus, for thicker gloves, thetotal solids content will tend to be within one of the following ranges:5% to 60%, 10 to 60%, 15 to 60%, 20 to 60%, 25 to 60%, 30% to 60%, 35%to 60%, 40-60%, 5 to 55%, 10% to 55%, 15 to 55%, 20 to 55%, 25 to 55%,30% to 55%, 35% to 55%, 40% to 55%, 5 to 50%, 10% to 50%, 15 to 50%, 20to 50%, to 50%, 30% to 50%, 35% to 50%, 40% to 50%, 45-55%, 50-60%, or40-50%.

The elastomeric film-forming composition of the invention can be used toform a self-supported or unsupported film. A self-supported orunsupported film is a film that exists without other structuralcomponents or layers that the film is adhered to or attached to.

In the art of the present invention, it is common to refer to the amountof the polymer as being 100 phr (per hundred parts “rubber”), and forthe relative amounts of the remaining components of the elastomericfilm-forming composition to be calculated as a number of parts comparedto the 100 phr of the polymer, by weight. Thus, for an amount ofcross-linking agent that is 1/100th that of the polymer in thecomposition by weight, the amount of cross-linking agent is referred toas 1.0 phr.

It is also common in the art to use the expression “latex” or “rubber”to refer to any polymer in a general sense. Accordingly, particularly inthe examples which follow, it should be understood that these terms havebeen used as short-hand to refer to the polymer of the dippingcomposition.

Polymer

The polymer that is used in the elastomeric film-forming composition ofthe present invention comprises a single polymer consisting ofchlorobutadiene units, to which one or more carboxylic acid residues oresters thereof are grafted. In these polymers the carboxylic acidresidues are covalently attached to the chlorobutadiene units which formthe backbone of the polymer.

The polymer may be referred to as a “carboxylate or ester substitutedpolychlorobutadiene” or a “carboxylate or ester graftedpolychlorobutadiene”.

The polymer backbone may be a homopolymer containing one type ofchlorobutadiene monomer, or a copolymer containing two or more differentchlorobutadiene monomers. Similarly, the carboxylic acid residues oresters thereof that are grafted to the polymer backbone may consist ofone type of carboxylic acid residues or esters thereof or more than onetype of carboxylic acid residues or esters thereof.

The polychlorobutadiene backbone comprises chlorobutadiene units. Insome embodiments, there are no carboxylic acid groups or esters thereofin the main chain of the polymer. The carboxylic acid residues arecovalently attached to the chlorobutadiene units as substituents on thepolychlorobutadiene. The polymer may be referred to as a “carboxylicacid- or ester-substituted polymer” or a “carboxylic acid- orester-grafted polymer”.

The stability of polychloroprene in general is poor compared to otherlatexes due to decomposition by autocatalytic dehydrochlorination.Therefore, polychloroprene is generally prepared at high pH to avoidsuch decomposition. In the present case, the carboxylic acid- orester-grafted polychlorobutadiene may be prepared at a pH in the rangeof from about 8.5 to about 13.5. Preferably, the carboxylic acid- orester-grafted polychlorobutadiene has a pH in the range of from about8.5 to 11, 9.0-11.5, 9.5-12,-12.5, 11-13, 11.5-13.5. It will beappreciated that the pH could be modified, such as by the addition ofacid or base to suit the purpose of the composition.

The shelf life of the carboxylic acid- or ester-graftedpolychlorobutadiene used in the elastomeric film-forming composition ofthe present invention may be affected by the presence of carboxylgroups. In some cases, the polymer and/or the elastomeric compositionmay be stored at lower temperature and the pH monitored and adjusted(for example, by addition of alkaline solutions preferably potassiumhydroxide and/or ammonium hydroxide), where necessary.

Carboxylate- or Ester-Grafted Polychlorobutadiene

The carboxylate- or ester-grafted polymer could be prepared by graftingone or more carboxylic acid residues or esters thereof onto a polymercontaining chloroprene units. The grafting step may be performed by thesupplier and the polymer provided to the manufacturer as the carboxylicacid- or ester-grafted polymer for use in the preparation of theelastomeric film-forming composition and ultimately the manufacture ofelastomeric films or dipped articles such as gloves. The grafting stepmay also be performed by the manufacturer as a first step in thepreparation of the elastomeric film-forming composition.

In the case where the grafting step is performed by the manufacturer,the flexibility in the grafted polymer produced may allow improvedprocessability, improved properties for the film or dipped articlesproduced from the composition and may result in a saving in the amountof material used in making the film.

It is often the case that commercially available polymer formulationscan vary and there may be differences between the polymers provided bydifferent suppliers. Therefore, where the manufacturer performs thegrafting step in situ, the grafted polymer can be produced with improvedconsistency, and the manufacturer can control the type of graftedpolymer produced or make certain adjustments to the grafting process tomake a grafted polymer that is most suitable for the intendedapplication of the elastomeric films or dipped articles that areultimately produced.

As one example, the process may be customised to produce a graftedpolymer having a particular amount of carboxylic acid or ester graftedto the polymer backbone. Carboxylic acid- or ester-graftedpolychlorobutadiene having a higher amount of carboxylic acid or esterin the polymer may be preferred for some applications, while acarboxylic acid- or ester-grafted polychlorobutadiene having a loweramount of carboxylic acid or ester in the polymer may be preferred forother applications. Conducting the grafting process in situ allows themanufacturer to control parameters such as the amount of carboxylic acidor ester grafted to the polymer backbone and to tailor the elastomericfilm-forming composition for its end use.

The grafting step is performed using standard methods, and it will beappreciated that any suitable grafting technique could be used to makethe polymer from polychloroprene and suitable carboxylic acids or estersthereof. The grafting step may be performed by one of the variousmethods described in “Polymer Grafting and Cross-linking” Edited by Dr.Amit Bhattacharya, Dr. James W. Rawlins, and Dr. Paramita Ray, JohnWiley & Sons, Inc., 2009, and in “Grafting: a versatile means to modifypolymers: Techniques, factors and applications” Bhattacharyaa, A. andMisrab, B. N., Progress in Polymer Science, 2004, Volume 29, Issue 8,pages 767-814, the contents of which are incorporated herein byreference.

Grafting is a method of modifying a polymer or a copolymer ofchlorobutadiene by covalently bonding carboxylic acid or ester groups tothe polymer chain. In particular, grafting is used to prepare acarboxylic acid- or ester-grafted polychlorobutadiene.

The grafting may be achieved by chemical means (for example by freeradical or ionic reaction), using radiation, photochemical orplasma-induced techniques, or by enzymatic grafting.

As one example, the grafted polymer may be formed by preparing asolution containing a polymer of chloroprene units and adding areactable carboxylic acid or ester residue. The polymer of chloropreneunits and the reactable carboxylic acid or ester residue may then besubjected to free radical or ionic reaction, exposed to radiation, aphotochemical stimulus, plasma-induced techniques or an enzyme in orderfor the reactable carboxylic acid or ester residues to be covalentlyattached to the polymer of chloroprene units.

In some embodiments, grafting is by chemical means and an initiatorproduces free radicals, which are transferred to the polymer andsubsequently react with the reactable carboxylic acid or ester residueto form the carboxylic acid- or ester-grafted polymer. In otherembodiments, irradiation may be used to form free radicals on thepolymer, which then react with the reactable carboxylic acid or esterresidue to form the carboxylic acid- or ester-grafted polymer. Ingeneral, the generation of free radicals can occur by indirect or directmethods. One example of the production of free radicals by an indirectmethod is the production of free radicals through redox reaction, suchas with persulfates. In some embodiments, a redox catalyst system isused.

In some embodiments, a carboxylic acid- or ester-graftedpolychlorobutadiene is prepared by combining a polychlorobutadienepolymer with a reactable carboxylic acid or ester residue in thepresence of a cross-linking agent or chain-transfer agent. Thecross-linking agent or chain transfer agent may, for example bediisopropyl xanthogen disulphide or an emulsifier stabilizer such aspolyvinyl alcohol (PVA). The polychlorobutadiene polymer, the reactablecarboxylic acid or ester residue and the cross-linking agent orchain-transfer agent may be combined in solution and may be emulsifiedto form an oil-in-water emulsion. Catalysts may be added as required toinitiate and maintain the grafting process. Examples of suitablecatalysts include sodium sulphite and potassium persulphate.

Grafting is typically carried out until the reactable carboxylic acid orester residue is largely or completely grafted onto the polymer. Forexample, complete conversion may be achieved when greater than 90% andpreferably about 98% of the reactable carboxylic acid or ester residuehas been grafted onto the polychlorobutadiene. The extent of graftingmay be verified by determining the amount of unreacted carboxylic acidor ester using analytical methods, and subtracting this amount from theamount of carboxylic acid or ester added.

It will be appreciated that any other suitable grafting technique couldbe used to make the carboxylic acid- or ester-graftedpolychlorobutadiene. Furthermore, the grafting technique used could bemodified, such as by the addition of catalysts, by using differentcross-linking agents or chain-transfer agents or by altering therelative amount of the components.

In some cases, it is important to control the pH during grafting, as thecarboxylic acid group lowers the pH and may destabilize the chloroprenepolymer. Typically, the grafting step is performed with slow addition ofthe carboxylic acid residues or esters thereof.

Grafting of polychloroprene latex by combining the carboxylic acid groupor derivative thereof (esters-acrylates) at the glove manufacturer endis possible with due care. It may be necessary to use suitable pHmodifiers, and/or emulsifying agents to perform the grafting step.Preferably, the polymer containing chloroprene units is grafted withesters of carboxylic acid residues and optionally subsequentlyconverting the esters to carboxylic acid residues. In some cases thecarboxylic acid residue may destabilize the polymer, or may behazardous. It may also be necessary to strip off the unreactedcarboxylic acid residues.

Chlorobutadiene Units

Any chlorinated butadiene units may be used to form the carboxylic acid-or ester grafted polychlorobutadiene of the present invention. Examplesof suitable chlorobutadiene units include 2-chloro-1,3-butadiene,2,3-dichloro-1,3-butadiene and combinations thereof.

In one embodiment, a combination of 2-chloro-1,3 butadiene and2,3-dichloro-1,3-butadiene are present in the polymer backbone, whichmay be subsequently grafted with the carboxylic acid or ester thereof.In another embodiment, 2-chloro-1,3 butadiene or2,3-dichloro-1,3-butadiene are used to form a homopolymer, which may besubsequently grafted with the carboxylic acid or ester thereof.

The number and type of chlorobutadiene units present in the polymer thatis used in the elastomeric film-forming composition may vary, and willdepend on the purpose for which the composition will be used. The numberof chlorobutadiene units, and the extent of chlorination of thosechlorobutadiene units can be expressed as a percentage by weight of thechlorobutadiene units present in the polymer.

In order to produce a polymer having a specific level of chlorination,the polychlorobutadiene can be prepared by adjusting the relativeamounts of chlorobutadiene and dichlorobutadiene used to form thepolychlorobutadiene.

In one embodiment, the polymer comprises from about 10 to about 60%chlorine by weight of the chlorobutadiene units present in the polymer.Preferably, the polymer comprises from about 10% to about 58%, about 25%to about 60%, about 25% to about 58%, about 30% to about 60%, about 30%to about 58%, about 30% to about 45% or about 35% to about 45% chlorineby weight of the chlorobutadiene units present in the polymer. Morepreferably, the polymer comprises about 40% chlorine by weight of thetotal polymer.

Where the chlorine content is at the lower end of this range, theresulting dipped article will be softer, more stable and of nominalstrength. Where the chlorine content is at the higher end of this range,the resulting dipped article will be tougher. It is believed that thehigher chlorine content increases the molecular weight and increasedbonding reactivity with ZnO.

Where a lower chlorine content is used, the elastomeric film-formingcomposition may be suitable for use in applications such as surgicalgloves, where a softer or more elastic film is able to provide thewearer with good tactile perception. For example, the chlorine contentsuitable for production of thinner, softer and more elastic films may bein the range of about 10 to 50%, such as about 10 to 45%, about 25% to45%, about 10 to 40%, about 25% to 40%, about 30 to 45%, about 30 to40%, about 10 to 35%, about 25% to 35%, about 20% to 30% or about 10 to30%.

Where a higher chlorine content is used, the elastomeric film-formingcomposition may be suitable for use in applications such as householdgloves, industrial or heavy duty gloves, where a more rigid, lesselastic film is required. For example, the chlorine content suitable forproduction of more rigid, less elastic films may be in the range ofabout 30 to 60%, such as about 30 to 58%, about 35 to 60%, about 35 to58%, about 40 to 60%, about 40 to 58%, about 40 to 55%, about 45 to 60%,about 45 to 58%, about 40 to 50%, about 50 to 60% or about 50 to 58%.

Carboxylic Acid Residues

Any carboxylic acid or ester residues may be used in the elastomericfilm-forming composition of the present invention. As one example, thecarboxylic acid or ester thereof may simply be a carboxylic acidsubstituent, —C(O)—OH, or an ester thereof, —C(O)—OR, wherein R is analkyl group. In some embodiments, the alkyl group has from 1 to 10carbon atoms or from 1 to 4 carbon atoms. As another example, thecarboxylic acid or ester may be a carboxylic acid or ester-containingmonomer.

Suitable carboxylic acid or ester-containing monomers includeethylenically unsaturated carboxylic acid or esters thereof. Thecarboxylic acid and/or derivative could be of any type, includingsaturated or unsaturated, mono, di, tri or multi carboxylic acid, or maybe aliphatic or aromatic in nature. Examples of suitable carboxylicacids include methacrylic acid, acrylic acid or terepthalic acid.Examples of suitable carboxylic acid derived esters are vinyl acetate,methyl acrylate, methacrylate ester, ethylenediol dimethacrylate and/orother related acrylate monomers.

In one embodiment, the carboxylic acid or ester has the formula:

CR¹H═CR²—C(O)—OR³

or

CR¹H═CR²—O—C(O)—R³

whereinR¹ is hydrogen, an alkyl radical containing 1 to 4 carbon atoms,—C(O)—OR⁴ or —R⁵—C(O)—OH, wherein R⁴ is hydrogen or an alkyl radicalcontaining 1 to 4 carbon atoms and R⁵ is an alkyl radical containing 1to 4 carbon atoms;R² is hydrogen, an alkyl radical containing 1 to 4 carbon atoms, or acarboxymethyl radical;R³ is hydrogen, an alkyl radical containing 1 to 4 carbon atoms, or—R⁶O—C(O)—CR⁷═CR⁸, wherein R⁶ is an alkyl radical containing 1 to 4carbon atoms, and R⁷ and R⁸ are each independently hydrogen or an alkylradical containing 1 to 4 carbon atoms; andcis or trans isomers thereof

Examples of suitable carboxylic acids or esters include acrylic acid,methacrylic acid, crotonic acid, fumaric acid, maleic acid, citraconicacid, glutaconic acid, vinyl acetate, methyl acrylate, methacrylateester, ethylenediol dimethacrylate, butanediol dimethacrylate (forexample, the commercially available 1,3, BDDMA by BASF could be used),methyl methacrylate (for example, the commercially available MMA by TheDOW Chemical Company or Rohm&Haas), butyl methacrylate (BMA) and glacialmethacrylic acid (GMAA), other related acrylate monomers or combinationsthereof.

The number and type of carboxylic acid or ester residues present in thegrafted polychloroprene polymer used in the elastomeric film-formingcomposition may vary, and will depend on the purpose for which thecomposition will be used. The number of carboxylic acid or esterresidues present in the grafted polychloroprene polymer can be expressedin parts by weight of the polymer. The carboxylic acid content is notspecifically limited.

In order to produce carboxylic acid- or ester-grafted polychloroprenehaving specific amounts of carboxylic acid or ester, the carboxylicacid- or ester-grafted polychlorobutadiene can be prepared by adjustingthe amount of the carboxylic acid or ester used relative to the amountof polychlorobutadiene used to form the polymer. The amounts ofcarboxylic acid or ester (or the extent of grafting or the degree ofcarboxylation of the polymer) may be verified by determining the amountof unreacted carboxylic acid or ester using analytical methods, andsubtracting this amount from the amount of carboxylic acid or esteradded.

In one embodiment, the carboxylic acid- or ester-graftedpolychlorobutadiene contains the carboxylic acid or ester in an amountof from 0.01% to 8% by weight of chlorobutadiene units present in thepolymer. In other words, the mole ratio of chloroprene to the CO₂H groupis 1:0.000196 to 1:0.1573, and the CO₂H group will be present onapproximately every 6 to every 5102 moles of the chlorobutadiene units.Expressed another way, in some embodiments from 0.02% to 15% of thechlorobutadiene units in the polymer are attached to a carboxylic acidgroup. Preferably, the polymer contains the carboxylic acid residue orester thereof in an amount of from about 0.5 to about 5%, about 0.5 toabout 4%, about 0.5 to about 3.5%, or from about 1% to about 2.5% byweight of the chlorobutadiene units present in the polymer.

Using a carboxylic acid- or ester-grafted polychlorobutadiene having acarboxylic acid or ester group in an amount of 0.01 to 8% by weight ofthe chlorobutadiene units present in the polymer may provide anelastomeric film having improved properties. As one example, havingcarboxylic acid or ester group in an amount of 0.01 to 8% by weight ofthe chlorobutadiene units present in the polymer allows production ofthin films, such as films having a thickness in the range of 0.01-3.0mm, such as 0.01-2.5 mm, 0.01-2.0 mm, 0.01-1.5 mm, 0.01-1.0 mm, 0.01-0.5mm, 0.01-0.4 mm, 0.01-0.3 mm, 0.01-0.2 mm, 0.02-0.2 mm, 0.01-0.10 mm,0.03-3.0 mm, 0.03-2.5 mm, 0.03-2.0 mm, 0.03-1.5 mm, 0.03-1.0 mm,0.03-0.5 mm, 0.03-0.4 mm, 0.03-0.3 mm, 0.03-0.2 mm, 0.03-0.10 mm,0.05-3.0 mm, 0.05-2.5 mm, 0.05-2.0 mm, 0.05-1.5 mm, 0.05-1.0 mm,0.05-0.5 mm, 0.05-0.4 mm, 0.05-0.3 mm, 0.05-0.2 mm, 0.05-0.10 mm,0.08-3.0 mm, 0.08-2.5 mm, 0.08-2.0 mm, 0.08-1.5 mm, 0.08-1.0 mm,0.08-0.5 mm, 0.08-0.4 mm, 0.08-0.3 mm, 0.08-0.2 mm, 0.08-0.10 mm,0.1-3.0 mm, 0.1-2.5 mm, 0.1-2.0 mm, 0.1-1.5 mm, 0.1-1.0 mm, 0.1-0.5 mm,0.1-0.4 mm, 0.1-0.3 mm, 0.1-0.2 mm, 0.15-3.0 mm, 0.15-2.5 mm, 0.15-2.0mm, 0.15-1.5 mm, 0.15-1.0 mm, 0.15-0.5 mm, 0.15-0.4 mm, 0.15-0.3 mm,0.15-0.2 mm, 0.02-0.08 mm, 0.03-0.08 mm, or 0.05-0.08 mm. As anotherexample, having carboxylic acid or ester group in an amount of 0.01 to8% by weight of the chlorobutadiene units present in the polymer allowsproduction of elastomeric films having a lower modulus at 300%, a lowermodulus at 500% and/or a higher elongation to break, such as a modulusat 300% of less than 660 psi, a stress at 500% of less than about 2400psi and/or an elongation to break of greater than about 520%.

The presence of the carboxylic acid residue or ester thereof in anamount at the lower end of the above ranges results in a highly flexibleor elastic elastomeric film or dipped article, however, theprocessability of such a composition is more complex. The presence ofthe carboxylic acid residue or ester thereof in an amount at the higherend of the above ranges results in a tougher elastomeric film or dippedarticle, however, the processability of such a composition is improved.Accordingly, a balance must be struck between the desired softness ofthe elastomeric film or dipped article and the processability of thecomposition.

The elastomeric film or dipped article made from a compositioncontaining a carboxylic acid- or ester-grafted polychlorobutadienehaving a lower amount of carboxylic acid or ester in the polymer may besuitable for use in applications such as surgical gloves, where a softeror more elastic film is able to provide the wearer with good tactileperception. For example, the carboxylic acid or ester content suitablefor production of thinner, softer and more elastic films may be in therange of about 0.01 to 5.0%, such as about 0.01 to 3%, 0.01 to 2.5%,0.01 to 2%, about 0.01 to 1.8%, about 0.01 to 1.6%, about 0.01 to 1.5%,about 0.01 to 1.4%, about 0.01 to 1.3%, about 0.01 to 1.2%, about 0.01to 1.1%, about 0.01 to 1%, about 0.01 to 0.9%, about 0.01 to 0.8%, about0.01 to 0.7%, about 0.01 to 0.6%, about 0.01 to 0.5%, about 0.01 to0.4%, about 0.01 to 0.3%, about 0.01 to 0.2%, about 0.01 to 0.1% orabout 0.01 to 0.05%.

The elastomeric film or dipped article made from a compositioncontaining a carboxylic acid- or ester-grafted polychlorobutadienehaving a higher amount of carboxylic acid or ester in the polymer may besuitable for use in applications such as household gloves, industrialgloves or heavy duty gloves, where a more rigid, less elastic film isrequired. For example, the carboxylic acid or ester content suitable forproduction of more rigid, less elastic or more durable films may be inthe range of about 0.5 to 8%, such as about 1 to 8%, about 0.5 to 6%,about 1 to 6%, about 0.5 to 7%, about 1 to 7%, about 1.5 to 7%, about1.5 to 6%, about 2 to 8%, about 2 to 7.5%, about 2 to 7%, about 2 to 6%,about 2.5 to 8%, about 2.5 to 7.5%, about 2.5 to 7%, about 2.5 to 6%,about 3 to 8%, about 3 to 7%, about 3 to 6%, about 4 to 8%, about 4 to7%, about 4 to 6%, about 5 to 8%, about 5 to 7%, about 5 to 6%, about 6to 8%, or about 6 to 7%.

Cross-Linking Agents

The carboxylic acid- or ester-grafted polychlorobutadiene can becross-linked with one or more cross-linking agents to produce theelastomeric film. Various types of cross-linking agents can be used.

Accelerators are one sub-class of cross-linking agents which releasesulphur, or act with sulphur-containing compounds, to acceleratesulphur-based covalent cross-linking of the elastomer-forming polymer.Generally, accelerators can be advantageous as they shorten the curing(vulcanisation) time, lower the curing temperature or decrease theamount of cross-linking agents required to be used in the composition.However, on the negative side, accelerators can give rise to allergicreactions, such as allergic contact dermatitis with symptoms includingerythema, vesicles, papules, pruritus, blisters and/or crusting.Examples of suitable accelerators include the carbamates such asthiocarbamates (e.g. zinc dibutyl dithiocarbamate (ZDBC), Zinc diethyldithiocarbamate (ZDEC)); thiurams (eg. tetraethylthiuram disulfide(TETD), Tetramethylthiuram disulphide (TMTD)); thiourea (Ethyl thiourea(ETU) and diphenylthiourea (DPTU); thiazoles (e.g. MercaptoBenzothiazoles (MBT), Mercapto Benzothiozole disulphide (MBTS), zinc2-mercaptobenzothiazole (ZMBT)); guanidines (e.g. Diphenylguanidine(DPG)) and aldehyde/amine-based accelerators (e.g.hexamethylenetetramine). Other examples are well known in the art andcan be obtained from various publicly available sources.

Another class of cross-linking agents are the ionic cross-linkingagents, which include metal oxides, metal hydroxides and peroxides(organic and inorganic). These work by ionically cross-linkingionically-crosslinkable groups in the elastomer-forming polymer. Forexample, a metal oxide cross-linker can work by ionically cross-linkingthe carboxylic acid groups of the carboxylic acid- or ester-graftedpolychlorobutadiene. Examples of suitable metal oxide cross-linkingagents include the multivalent metal oxide cross-linking agents, such aslead oxide, magnesium oxide, barium oxide, zinc oxide, manganese oxide,copper oxide, aluminium oxide, nickel oxide and combinations thereof.Examples of suitable metal hydroxide cross-linking agents include zinchydroxide, aluminium hydroxide, magnesium hydroxide, and other metalhydroxides, such as barium hydroxide, manganese hydroxide, copperhydroxide, and nickel hydroxide. An example of a peroxide cross-linkingagent is 1,1-di(t-butylperoxy)-3,3,5-trimethylcyclohexane, which can bepurchased under the trade name Trigonox 29-40B-pd. Other cross-linkingagents that are suitable for use in the elastomeric film-formingcomposition are selected from, but not restricted to cross-linkingmonomers, reactive oligomers, polyisocyanate oligomers, functional,cross-linkable polymers, derivatives of ethylene glycol di(meth)acrylate(such as ethylene glycol diacrylate, di(ethylene glycol) diacrylate,tetra(methylene/ethylene glycol) diacrylate, ethylene glycoldimethacrylate (EDMA), di(ethylene glycol) dimethacrylate (DEDMA),tri(methylene/ethylene glycol) dimethacrylate, tetraethylene glycoldimethacrylate (TEDMA)), derivatives of methylenebisacrylamide (such asN,N.-methylenebisacrylamide, N,N.-methylenebisacrylamide, N,N.-(1,2dihydroxyethylene)bisacrylamide), formaldehyde-free cross-linking agents(such as N-(1-Hydroxy-2,2-dimethoxyethyl)acrylamide), divinylbenzene,divinylether, diallyl phthalate, divinylsulfone and the like. Some ofthese cross-linking agents are commercially available and are suppliedby companies such as Aldrich. Combinations of these cross-linking agentscan also be used.

The amount of cross-linking agent is typically in the range 0.5-15.0phr. In some embodiments, the amount of cross-linking agent is suitablywithin one of the following ranges: 0.5-15.0 phr, 1.0-15.0 phr, 1.5-15.0phr, 0.5-13.0 phr, 1.0-13.0 phr, 1.5-13.0 phr, 0.5-11.0 phr, 1.0-11.0phr, 1.5-11.0 phr, 0.5-10.0 phr, 1.0-10.0 phr, 1.5-10.0 phr, 0.5-8.0phr, 1.0-8.0 phr, 1.5-8.0 phr, 0.5-7.0 phr, 1.0-7.0 phr, 1.5-7.0 phr,2.0-8.0 phr, 2.5-10.0 phr, 5.0-10.0 phr, 3.0-7.0 phr, 3.0-6.0 phr,4.0-7.0 phr, 4.0-6.0 phr, 4.0-5.0 phr, 2.0-5.0 phr, 2.0-4.0 phr, 3.0-4.0phr, 6-10 phr, 7-10 phr, 6-8 phr, 5-9 phr, 8-10 phr, 0.01-3.5 phr,0.01-3.0 phr, 0.01-2.0 phr, 0.01-1.5 phr, 0.01-1.0 phr or 0.01-0.5 phr.

A metal oxide can serve two functions in the elastomeric film-formingcompositions of the present invention. Firstly the metal oxide canneutralize hydrochloric acid that is formed from the slowdehydrochlorination of the chlorobutadiene units, and secondly, themetal oxide can cross-link the functional groups to provide excellentbond strength and heat resistance. The allyl chloride structures in thecarboxylic acid- or ester-grafted polychlorobutadiene function as majorcross-linking sites by reaction with metal oxides. For at least thisreason, ionic cross-linking agents such as metal oxides and peroxidesmay need to be used in higher quantities than they would typically beused. For example, in some embodiments, zinc oxide may be added in veryhigh quantity varying from 3 to 10 parts or 5 to 10 parts per hundredparts of dry rubber. The zinc oxide requirement for other syntheticelastomers like acrylonitrile, polyisoprene and even natural rubber maybe lower, for example, 2 phr or even less.

The suitable vulcanization activators comprise metal oxides, such aslead oxide, magnesium oxide, barium oxide, zinc oxide, manganese oxide,copper oxide, aluminium oxide and nickel oxide, preferably zinc oxide.

A further class of cross-linking agents are the covalent cross-linkingagents, which include sulphur and sulphur-containing vulcanising agents.These work by covalently cross-linking unsaturated double bonds presentin the elastomer-forming polymer. The sulphur can be present in the formof elemental sulphur. The sulphur in sulphur-containing vulcanisingagents can also be donated by organic sulphuric compounds, for exampleTMTD (Tetramethylthiuram Disulfide). Sulphur donors orsulphur-containing vulcanising agents such as this one are likely tocontribute to chemical allergies and it is preferred to keep their useto a minimum in the manufacture of gloves when allergic content is anissue. Thus, if used, the sulphur is preferably present in the form ofelemental sulphur.

Generally, the amount of cross-linking determines the elasticity of theelastomeric film. Therefore, the amount and type of cross-linking agentwill contribute to the extent of cross-linking and the elasticity of thefinal elastomeric film.

For ionic cross-linking agents such as metal oxide and peroxidecross-linking agents, when used, the amount is typically in the range1.0-10.0 phr. The amount of metal oxide cross-linking agent is suitablywithin one of the following ranges: 1.0-10.0 phr, 2.0-8.0 phr, 2.5-10.0phr, 5.0-10.0 phr, 3.0-7.0 phr, 3.0-6.0 phr, 4.0-7.0 phr, 4.0-6.0 phr,4.0-5.0 phr, 2.0-5.0 phr, 2.0-4.0 phr, 3.0-4.0 phr, 6-10 phr, 7-10 phr,5-8 phr, 5-6 phr, 6-8 phr, 5-9 phr, or 8-10 phr. In some embodiments,where the degree of carboxylation of the polymer is lower, the amount ofmetal oxide used will be at the higher end of the range. For example,The amount of metal oxide cross-linking agent is suitably within one ofthe following ranges: 3-10 phr, 5-10 phr, 6-10 phr, 7-10 phr, 5-8 phr,5-6 phr, 6-8 phr, 5-9 phr, or 8-10 phr. In some embodiments, where theamount of carboxylic acid or ester in the carboxylic acid- orester-grafted polychlorobutadiene is higher, the amount of metal oxideused will be at the lower end of the range. For example, the amount ofmetal oxide cross-linking agent is suitably within one of the followingranges: 1.0 to 5 phr, 2.0 to 5 phr, 2.0 to 4.0 phr, 2.5 to 5 phr or 3.0to 5.0 phr. However, the effect of the presence of additional or excessmetal-oxides may be diminished or insignificant where other elastomers,such as the second elastomer, are added to the composition and blendedwith the polymer comprising chlorobutadiene units and one or morecarboxylic acid residues or esters thereof.

Sulphur requires high energy at curing (thus high curing temperatureand/or time) compared to other cross-linking agents. However, sulphurdoes provide the resulting dipped articles, such as gloves, with greaterchemical resistance, and therefore it may be desired for this reason.The amount of sulphur is suitably within one of the following ranges:0.0-3.5 phr, such as 0.01-3.5 phr, 0.01-3.0 phr, 0.01-2.0 phr, 0.01-1.5phr, 0.01-1.0 phr, 0.01-0.5 phr, 0.5-3.5 phr, 0.5-3.0 phr, 0.5-2.0 phrand 0.5-1.5 phr.

In some embodiments, where the amount of carboxylic acid or ester in thecarboxylic acid or ester in the carboxylic acid- or ester-graftedpolychlorobutadiene is higher, it could be possible to reduce and eveneliminate accelerators from the elastomeric film-forming composition ofthe invention. For example, for dipped articles having a larger filmthickness, accelerator elimination is feasible where the strength is notcompromised. However, further improved physical characteristics may beobtained using an accelerator, such as further improved softness. Wherethis property is desirable, it will be preferable to use sufficientaccelerators. Accordingly, the composition for producing the elastomericfilm will be accelerator-free in some embodiments, and will furthercomprise an accelerator in other embodiments.

The amount of accelerator is suitably between 0.1-2.0 phr, such asbetween 0.1-1.5 phr, 0.1-1.0 phr, 0.2-1.0 phr, 0.3-2.0 phr, 0.3-1.5 phr,0.2-0.6 phr, 0.5-2.0 phr, or 0.5-1.5 phr. Suitable accelerators includemercaptobenzothiazoles and derivatives thereof, dithiocarbamates andderivatives thereof, sulphur donors, guanidines, thio-urea andaldehyde-amine reaction products.

In some embodiments, the composition will be free of a hardening amountof a hardener. Hardeners are often used in adhesive compositions toharden the adhesive when it is mixed with other components such asresins. The composition of the invention may be used in the preparationof films and dipped articles, such as gloves. In some embodiments, thecomposition of the invention may be used to form dipped articles such asgloves which are elastic. The addition of a hardener would result information of elastomeric films which are hard or stiff and may in somecases be brittle.

In one embodiment, the cross-linking agents used in the elastomericfilm-forming composition of the present invention are selected from thegroup consisting of sulphur, a sulphur-containing vulcanising agent,organic peroxide, metal oxide, metal hydroxide and combinations thereof.Preferably, the composition contains a combination of sulphur or asulphur-containing vulcanising agent, and a metal oxide or metalhydroxide. The use of the combination of cross-linking agents, such assulphur and metal oxide, provides a polymer having ionic cross-linkingas well as covalent cross-linking across the unsaturated double bonds ofthe carboxylic acid- or ester-grafted polychlorobutadiene. The metaloxide will form ionic bonds to the carboxylic acid or ester groups andto the chlorine in the polymer. Formation of ionic bonds requires lessenergy and allows quicker production of the elastomeric film-formingcomposition. The sulphur will form covalent bonds with the butadiene,particularly at carbon sites. Formation of these covalent bonds requireshigher energy, however, the resulting elastomeric film may have improvedpermeation characteristics. Accordingly, the combination of these typesof cross-linking agents provides a balance between the time and energyrequired to produce the elastomeric film and the performance of theelastomeric film. The combination of ionic and covalent cross-linking inthe polymer may also provide an elastomeric film having improvedproperties, such as improved strength and durability of the film. Theamount and type of cross-linking also contributes to the elasticity ofthe film.

Second Elastomer

The carboxylic acid- or ester-grafted polychlorobutadiene may be blendedwith one or more alternative elastomers also referred to as a secondelastomer. For example, the alternative elastomers may be lower costelastomers, which are added in order to reduce the cost of the endproduct. The type and amount of the one or more second elastomers addedto the elastomeric film-forming composition will depend on thecarboxylic acid- or ester-grafted polychlorobutadiene used in thecomposition, and the intended use of the composition.

Examples of suitable second elastomers include synthetic elastomers orsynthetic rubbers such as nitrile rubber, styrene butadiene rubber,butyl rubber, polyisoprene, polychloroprene, polybutadiene,polyvinylchloride, polyurethane, styrene diblock copolymers, styrenetriblock copolymers, acrylic polymers or other synthetic elastomers ormixtures thereof. The second elastomer may be carboxylated (for example,by grafting or copolymerizing and or mixtures thereof), non-carboxylatedor a mixture of carboxylated and non-carboxylated elastomers, or amixture of elastomers having varied degrees of carboxylation.

In some embodiments, the amount of the second elastomer would not exceed95% of the polymer component of the elastomeric film-forming compositionon a dry basis. The polymer component of the elastomeric film-formingcomposition includes the amount of the carboxylic acid- or ester-graftedpolychlorobutadiene and the amount of the second elastomer. For example,the amount of the second elastomer may be in the range of from 0 to 95%of the polymer component of the elastomeric film-forming composition ona dry basis, such as about 5-95%, 0-65%, 0-50%, 5-65%, 10-95%, 10-65%,15-95%, 15-65%, 20-95%, 20-65%, 25-95%, 25-65%, 30-95%, 30-65%, 35-95%,35-65%, 40-95%, 40-65%, 50-60%, 50-65%, 50-95%, 60-65%, 60-75%, 60-80%,60-95%, 70-90%, 70-95%, 80-95%, 0-5%, 5-10%, 10-15%, 15-20%, 20-25%,25-30%, 30-35%, 35-40%, or 40-50%.

It will be appreciated that the blended composition will retain thefavourable properties provided by the use of the carboxylic acid- orester-grafted polychlorobutadiene. Preferably, the amount of the secondelastomer is less than about 75% of the polymer component of theelastomeric film-forming composition on a dry basis, such as 0-75%, lessthan 65%, 0-65%, 5-75%, 5-65%, 10-75%, 10-65%, 15-75%, 15-65%, 20-75%,20-65%, 25-75%, 25-65%, 30-75%, 30-65%, 35-75%, 35-65%, 40-75% or40-65%.

In some embodiments, the amount of the second elastomer may depend onthe amount of carboxylic acid or ester in the carboxylic acid- orester-grafted polychlorobutadiene. A balance must be struck between theamount of carboxylic acid or ester in the carboxylic acid- orester-grafted polychlorobutadiene and the amount of the second elastomerthat is used in the composition in order to produce an elastomeric filmor dipped article (such as a glove) having a suitable thickness, asuitable amount of material used to form the film or article, and havingsuitable properties for its use. Accordingly, the amount of the secondelastomer used will depend on the carboxylic acid- or ester-graftedpolychlorobutadiene that is used and the end product to be produced.

As one example, a more rigid, less elastic or more durable film may beproduced when a high amount of carboxylic acid or ester is present inthe carboxylic acid- or ester-grafted polychlorobutadiene and the amountof the second elastomer used in the composition is towards the upper endof the range of 0-95% of the polymer component of the elastomericfilm-forming composition on a dry basis. For example, when thecarboxylic acid or ester content is in the range of about 1 to 8%, theamount of the second elastomer may be within one of the followingranges: 50-60%, 50-65%, 50-95%, 60-65%, 60-75%, 60-80%, 60-95%, 70-90%,70-95%, 80-95%, or 0-50%.

As another example, a softer, more elastic film may be produced when alow amount of carboxylic acid or ester is present in the carboxylicacid- or ester-grafted polychlorobutadiene and the amount of the secondelastomer used in the composition is towards the lower end of the rangeof 0-95% of the polymer component of the elastomeric film-formingcomposition on a dry basis. For example, when the carboxylic acid orester content is in the range of about 0.01 to 5%, the amount of thesecond elastomer may be within one of the following ranges: 0-5%, 5-10%,10-15%, 15-20%, 20-25%, 25-30%, 30-35%, 35-40%, 40-50%, or 50-95%.

Other Components or Additives

Other components or additives may be included in the composition caninclude one or more additives selected from the group consisting ofplasticizers, antiozonants, stabilisers such as pH stabilisers,emulsifiers, antioxidants, vulcanising agents, polymerisationinitiators, pigments, fillers, colourising agents and sensitisers.

Stabilisers may be used in the elastomeric film-forming composition. Thestabilizer may be, for example, an oleate, stearate or other non-ionicsurfactants. The elastomer-forming polymer can be diluted with asolution of a stabilizer, such as potassium hydroxide, ammoniumhydroxide and/or sodium hydroxide. The amount of stabiliser used isdependent on the polymer used in the elastomeric film-formingcomposition, the pH of the composition and other factors. The stabilisercan range from 0.1-5.0 phr, e.g. 0.5 to 2 phr, preferably 1.0 to 1.5phr, which is diluted with water, preferably filtered water orde-ionized water, or water having a total solid content of around 5 ppmlevel-water.

Emulsifiers may be used in the elastomeric film-forming composition.Suitable emulsifiers include sodium alkyl sulphates or other non-ionicand ionic surfactants. The amount of emulsifier used is dependent on theon the polymer used in the elastomeric film-forming composition, the pHof the composition and other factors. The amount of emulsifier can rangefrom about 0.1 to 5 phr, 0.5 to 5 phr, 0.1 to 3 phr or 0.5 to 3 phr.

pH stabilisers may be used to avoid the possibility of destabilization,which is possible where the elastomer-forming polymer containscarboxylic acid groups. Suitable pH stabilisers include potassiumhydroxide, ammonium hydroxide and/or sodium hydroxide. Preferably, thepH stabiliser is potassium hydroxide. A diluted stabilizer solution canbe mixed with the elastomer-forming polymer. The pH of the mixture issuitably adjusted to between about 8.5 to about 13.5, or between about8.5 to about 11.0. The cross-linking agent(s) can then be added to themixture. The amount of pH stabilizer can range from about 0.1 to 3.0phr, 0.1 to 2.5 phr, 0.1 to 2.0 phr, 0.1 to 1.5 phr, 0.1 to 1.0 phr, 0.1to 0.5 phr, 0.2 to 3.0 phr, 0.2 to 2.5 phr, 0.2 to 2.0 phr, 0.2 to 1.5phr, 0.2 to 1.0 phr, 0.2 to 0.5 phr, 0.5 to 3.0 phr, 0.5 to 2.5 phr, 0.5to 2.0 phr, 0.5 to 1.5 phr or 0.5 to 1.0 phr.

Antiozonants may be used in the elastomeric film-forming composition.Suitable anitozonants include paraffinic waxes, microcrystalline waxesand intermediate types (which are blends of both paraffinic andmicrocrystalline waxes). The amount of antiozonant can range from about0.1 to 5.0 phr, 0.1 to 3.0 phr, 0.1 to 1.5 phr, 0.5 to 5.0 phr, 0.5 to3.0 phr, or 0.5 to 1.5 phr.

Antioxidants may be added to the elastomeric film-forming composition ofthe present invention. Suitable antioxidants include hindered arylaminesor polymeric hindered phenols, and Wingstal L (the product of p-cresoland dicyclopentadiene). The antioxidant may, for example, be added in anamount ranging from about 0.1-5.0 phr, such as 0.1-3.0 phr, 0.5-3.0 phr,0.1-1.5 phr, 0.1-1.0 phr or 0.3-0.5 phr.

Pigments, such as titanium dioxide, are selected for their pigmentation,or to reduce the transparency of the final elastomeric film. Pigmentsmay also be referred to as opaqueness providers. The amount of pigmentmay, for example, be added in amounts ranging from about 0.01-10.0 phr,such as 0.01-5.0 phr, 0.01-3.0 phr, 0.01-2.0 phr, 0.01-1.5 phr, or1.5-2.0 phr and colorants can also be added in the desired amounts. Themixture is then diluted to the target total solids concentration by theaddition of a liquid, such as water. The pigments used in theelastomeric film-forming composition may be selected from the groupconsisting of EN/USFDA approved dyes.

Rubber reoderants may be used in the elastomeric film-formingcomposition. Suitable rubber reoderants include perfume oils of naturalor synthetic origins. The amount of rubber reoderant can range fromabout 0.001 to 2.0 phr.

Wetting agents may be used in the elastomeric film-forming composition.Suitable wetting agent emulsifiers include anionic surfactants likesodium dodecyl benzene sulphonate or sodium lauryl ether sulphate, ornon-ionic ethoxylated alkyl phenols such as octylphenoxy polyethoxyethanol or other non-ionic wetting agents. The amount of wetting agentcan range from about 0.001 to 2.0 phr.

Defoamers or anti-foam may be used in the elastomeric film-formingcomposition. Defoamers may be chosen from naphthalene type defoamers,silicone type defoamers and other non-hydrocarbon type defoamers ordefoamers of refined vegetable origin. The amount of defoamers can rangefrom about 0.001 to 2.0 phr, such as about 0.001-1.0 phr, 0.001-0.1 phr,0.001-0.01 phr.

The carboxylic acid- or ester-grafted polychlorobutadiene could also beblended with an inorganic filler. Suitable inorganic fillers includecalcium carbonate, carbon black or clay. Preferably, the amount ofinorganic filler included in the blend would not exceed 30% either aloneor in combination. It will be appreciated that the blended compositionwill retain the favourable properties provided by the use of thecarboxylic acid- or ester-grafted polychlorobutadiene.

Sensitisers are chemicals that can be used in compositions for producingelastomeric films to control the amount of the composition that willremain coated on the mould during dipping. Examples of sensitisers knownin the art that can be used in the composition for producing anelastomeric film include polyvinyl methylether, polypropylene glycol,ammonium nitrate and ammonium chloride. When used, the amount ofsensitiser will be chosen based on the desired film thickness to remainon the mould during dipping, and will generally be between 0.01-5.0 phr.For thinner films, the amount will generally be between about 0.01 to2.0 phr, such as, about 0.1 to 1.0 phr. When other techniques are usedfor controlling the film thickness on the mould, such as the use ofpre-dipping the mould into coagulant before undertaking the multipledipping into the composition for producing the elastomeric film, thecomposition for producing an elastomeric film may not comprise asensitiser.

In some embodiments, the composition will be free of a tackifier.Tackifiers are often used in adhesive compositions, particularlypressure sensitive adhesives, to improve the stickyness of the adhesiveor the ability of the adhesive to form an immediate bond with a surfaceupon contact. Tackifiers are usually resins, such as rosins and theirderivates, terpenes and modified terpenes, aliphatic, cycloaliphatic andaromatic resins, hydrogenated hydrocarbon resins, terpene-phenol resinsor mixtures thereof. The composition of the invention may be used in thepreparation of films and dipped articles, such as gloves. The additionof a tackifier would result in formation of sticky elastomeric filmswhich are not suitable for use in articles, such as gloves.

Those skilled in the art will readily be able to vary the components ofthe elastomeric film-forming composition to suit the particular polymerused as well as the particular final article desired. It will also beunderstood by those of skill in the art that specific chemicals orcompounds which have been listed above are intended to be representativeof conventional materials that may be used in formulating theelastomeric film-forming composition and are merely intended asnon-limiting examples of each such component of the composition.

Preparation of the Elastomeric Film-Forming Composition

The composition for producing an elastomeric film can be prepared bymixing the carboxylic acid- or ester-grafted polychlorobutadiene withone or more cross-linking agents, optionally one or more additives andoptionally a second elastomer, in a liquid (e.g. water). As describedabove, the carboxylic acid- or ester-grafted polychlorobutadiene or thepolymer in combination with the other components are diluted with aliquid to reach the desired total solids content of the composition.

Suitable additives or other components as described above may beincluded in the composition, and may be added to the polymer beforeaddition of the cross-linking agent, or added to the mixture of thepolymer and the cross-linking agent.

The preparation of the composition includes steps known in the art, andthe composition can be prepared in a conventional manner.

Typically, the powder components of the composition will be combined andmilled using suitable milling equipment to reduce the particle size to asuitable range. Preferably, the average particle size is below 5microns. Uniform particle size is desirable, and coarse milling mayresult in non-uniform particles and therefore a non-uniform film, whichcan result in high fluctuation in film properties.

When used, the surfactant and the pH stabilizer are added to the liquid(e.g. water) and mixed properly without any foam formation. This liquidis then used to dilute the polymer or a blend of the polymer with asecond elastomer, and other additives or components to the desired totalsolids content. The total solids content of the elastomeric film-formingcomposition will depend on the planned film thickness.

The pH of the dispersion may then be adjusted as necessary, preferablyto a pH within the range of 8.5 to 13.5 (e.g. a pH above 9 or preferablya pH between 10 and 11). Any high variation between the diluted polymerand dispersion will result in coagulation from the micro level to themacro level.

When the components have been mixed uniformly or to homogeneity, otheradditives such as colorants and emulsifiers are added. The elastomericfilm-forming composition is then left for maturation. The length of thematuration may vary depending on the level of cross-linking agent andthe degree of carboxylation of the polymer. Generally, the compositionwill be left for a minimum of 12 to 18 hours, while in some casesmaturation could be conducted over a period of days depending upon therequirements for preparing the dipped article and the level ofcross-linking agents present. The compounded elastomeric filmcomposition with suitable additives could be prematured by holding thecomposition at a controlled elevated temperature. For example, theelastomeric film composition could be held at 20° C. to 60° C. for aperiod of, for example, about 4 hours to about 24 hours depending on thetemperature, degree of carboxylation of the polymer, the amount and typeof vulcanization activators and accelerators, and type and quantity ofpH stabilizer and emulsifier stabilizer and wetting agents/surfactants.

Preparation of the Elastomeric Film

The manufacture of the elastomeric film may use conventional equipment.

Optional Step (a) Dipping the Former into a Coagulant

A suitable former, which is based on the shape of the article to beproduced (e.g. flat for a film or glove-shaped for a glove) can bedipped into a coagulant. The cleanliness of the former is an importantaspect with respect to the pin hole formation in the elastomeric film orthe cleanliness of the elastomeric film. Hence the former, which isnormally made of a ceramic material, will be serially dipped in mildacid solutions, water, and/or alkaline solutions, and passed throughbrushes and hot water. The sequence could be altered depending on thecleaning requirements. In some embodiments, cleaning of the formerinvolves dipping the former in acid solutions and alkaline solutions.

Following cleaning, the former is passed through a dryer so that theadhering water is removed by evaporation. The dryer temperature istypically above 105° C. and could be adjusted according to the linespeed and oven length. It is preferable the former is dry beforeentering the next station.

The former, dried as described above, is then dipped into a coagulantleaving a thin coating of the coagulant on the surface of the former. Insome embodiments, the coagulant is a salt solution containing ions. Inthis embodiment, dipping the former into the coagulant leaves a thincoating of the charged ions on the surface of the former. The chargedion coating can assist in controlling the amount composition for formingthe elastomeric film that will subsequently remain on the surface of theformer after dipping into the composition, through charge interactions.

The ions may be cationic (as in the case of, for example, sodiumion-containing coagulants or calcium ion-containing coagulants) oranionic, and the choice will be based on the identity of the elastomericpolymer. In some embodiments, the coagulant will have a pH greater than7, such as pH 8 to 10.

Generally metal ion solutions containing cations are suited to a broadrange of elastomeric polymers. Examples of such metal salt ions aresodium, calcium, magnesium, barium, zinc, and aluminium. The counterions may be halides (such as chloride), nitrate, acetate or sulphate,amongst others. In the case of calcium ion-containing coagulants, thecalcium ions can be provided as a solution of calcium nitrate or calciumchloride.

The coagulant may also include any other agents, such as wetting agents(such as fatty alcohol ethoxide or other suitable surfactants),anti-tack agents, anti-foaming agents and/or mould release agents, suchas silicon emulsions, polymer release agents and metallic stearates,examples of which are zinc, calcium and potassium stearates.

The concentration of ions in the coagulant can broadly be in the rangeof 0.0-50% by weight of the coagulant solution (measured as the compoundof the multivalent ion in the solution of the multivalent ions),depending on the desired thickness of the elastomeric film layers andthe number of layers to be applied (i.e. one layer or two or morelayers). In the case of thinner layers, the concentration is suitably inthe range of 0.0-20%, 0.0-15%, 0.0-12%, 1.5-20%, 1.5-15%, 1.0-10%,1.5-10%, 4-10%, 5-10%, 5-35%, 10-30%, 7-40%, 8-50% and 5-45%.Preferably, the concentration is in the range of 10-30%. The amounts ofother components such as wetness and anti-tack agents are dependent onthe properties desired through the use of these agents, and will varyaccordingly.

The coagulant may also include metallic stearates in a concentration inthe range of about 0.1-5.0% by weight, suitable wetting agents in aconcentration in the range of about 0.001-1.0%, and/or antifoamingagents in a concentration in the range of 0.001-1.0% by weight.

The duration or dwell time for the mould in the coagulant is suitablybetween 1 and 30 seconds. In some embodiments, the dwell time for themould in the coagulant is 1 to 10 seconds. In some embodiments, thedwell time for the mould in the coagulant may be longer than 30 seconds.The temperature of the coagulant into which the mould is dipped may, forexample, be between 30° C.-80° C.

Prior to dipping the former into the coagulant, the former may besubjected to heating. The heating may form a part of a preliminary mouldwashing and drying procedure. The mould may in this case be heated to asurface temperature in the range of 25° C. to 85° C., for example atemperature in the range of 30° C. to 70° C.

Optional Step (b) Drying or Partially Drying the Coagulant-Dipped Former

If the former is dipped into a coagulant, following this step the formeris dried or partially dried.

Drying (or partial drying) is a step that may be repeated in severalstages during the production of the multi-layered elastomeric film ordipped article. At each drying or partial drying step, the drying may beperformed by any suitable technique or equipment known in the art,including the application of hot air or radiant heat, or a dryingradiation source such as infra-red (IR) and far IR radiation. This canbe performed in an oven or any other suitable drying equipment orenvironment. In the case of drying in an oven, or under the influence ofhot air or radiant heat, the former may be passed through the dryingzone, which applies heat at an elevated temperature, for a period oftime that is sufficient to drive off the excess moisture/liquid to asufficient degree of dryness. In the case of drying the coagulantremaining on the former, the drying zone (such as oven) may for examplebe held at, or apply, heat at a temperature of between 50° C.-250° C.Typically, the temperature is maintained above 105° C. to enable waterevaporation. In some embodiments, the temperature is maintained at fromabout 110° C. to about 130° C. Depending on the method used for drying,the temperature may be adjusted according to factors such as line speed,the length of the drying zone and the drying time.

The former typically remains in this zone (or progresses through thiszone) for a period of time sufficient to reach the target level ofdrying, and optionally a target surface temperature of the coagulant onthe former. This may be between 25° C.-85° C., for example between 40°C.-70° C.

The surface temperature of a coating on the former (in this case, thecoagulant) can be tested by any suitable technique. One example involvesthe use of a device to measure the surface temperature of an object bythe infra-red energy emitted by the object. An example of a device ofthis type is the Thermo-Hunter, model: PT-2LD produced by Optex Co. Ltd.Other techniques for measuring the surface temperature of the film areknown in the art.

Step (i) Dipping the Former into the Elastomeric Film FormingComposition of the Invention to Produce a Layer of Elastomeric FilmForming Composition on the Former

Prior to the step of dipping the former into the elastomericfilm-forming composition, the elastomeric film-forming composition maybe seasoned or matured in a holding tank. As described above, the lengthof the maturation may vary depending on the level of cross-linking agentand the degree of carboxylation of the polymer. Generally, thecomposition will be left for a minimum of 12 to 18 hours, while in somecases maturation could be conducted over a period of days depending uponthe requirements for preparing the dipped article and the level ofcross-linking agents present. The elastomeric film-forming compositiontogether with any suitable additives could be prematured by holding thecomposition at a controlled elevated temperature. For example, theelastomeric film-forming composition could be held at 20° C. to 60° C.for a period of, for example, about 4 hours to about 24 hours dependingon the temperature, degree of carboxylation of the polymer, the amountand type of vulcanization activators and accelerators, and type andquantity of pH stabilizer and emulsifier stabilizer and wettingagents/surfactants.

The former is dipped into the composition for producing an elastomericfilm, embodiments of which have been described in detail above.

The former is in the dipping tank for an amount of time to ensure theformer is evenly coated, but not so long as to develop a thicker coatingthan necessary. Depending on the required thickness of the coating, thedwell time of the former in the dipping tank may be between about 1-60seconds, such as between about 5 to 60 seconds, 1 to 30 seconds, 1 to 10seconds or 2.0 to 7.0 seconds.

The temperature of the composition into which the former is dipped isgenerally within the range of 10° C. to 60° C., such as 10° C. to 50°C., 15° C. to 50° C., 20° C. to 50° C., 25° C. to 50° C., 25° C. to 45°C., 20° C. to 40° C. or 20° C. to 35° C. Preferably, the compositioninto which the former is dipped is constantly cooled with chilled waterand the latex bath temperature is kept between 20-35° C., such as 20° C.to 30° C. and more preferably at 25° C. In some embodiments, thecomposition is constantly circulated in the tank to avoid creaming andsettling of the chemicals contained in the elastomeric film-formingcomposition.

Preferably, the surface temperature of the former does not exceed thetemperature of the elastomeric film-forming composition by more than 80°C. It has been found by the applicant that if the surface temperature ofthe former is more than 80° C. higher than the temperature of thecomposition for producing an elastomeric film, shrinkage of the coatingof elastomeric film-forming composition on the former may occur. In someembodiments, the surface temperature of the former is lower than thetemperature of the elastomeric film-forming composition. However,typically, the surface temperature of the former is about 20° C. to 60°C. higher than the temperature of the elastomeric film-formingcomposition.

Step (ii) Drying or Partially Drying the Layer of Elastomeric FilmForming Composition on the Former

The coagulated wet film is partially air dried so that the wet film getsome strength before entering to the series of pre-leach tanks whereambient water or heated water (preferably around 50° C.) is continuouslyreplenished to scavenge out the extractable surfactants and othersoluble chemicals including nitrates.

The coating or layer of elastomeric film-forming composition on themould is then dried or partially dried, to reduce the water content offrom zero to above 22%. When the elastomeric film-forming composition ispartially dried, it may have a water content in excess of 22% by weight,between 22% and 80%, for example, to 25% to 75%, 30% to 77% or 25% to60%.

The drying or partial drying may be conducted using the same type ofdrying technique as described above in relation to step (b), usingconditions necessary to reach a state of complete or partial dryness.

The drying or partial drying may be performed by any suitable techniqueor equipment known in the art, including the application of hot air orradiant heat, or a drying radiation source such as infra-red (IR) andfar IR radiation. This can be performed in an oven or any other suitabledrying equipment or environment.

When drying in an oven, or under the influence of hot air or radiantheat, the former bearing the layer or coating of elastomericfilm-forming composition may be passed through the drying zone, whichapplies heat at an elevated temperature, for a period of time that issufficient to drive off some or all of the excess moisture/liquid to asufficient degree of complete or partial dryness. In this case, thedrying zone (such as oven) may be held at, or apply, heat at atemperature of between about 50° C. to about 300° C., such as about 100°C. to about 300° C. (depending on the drying time). Depending on themethod used for drying, the temperature may be adjusted according tofactors such as line speed, the length of the drying zone and the dryingtime.

The drying time period may be between 2-300 seconds (depending on thetemperature of the oven). Generally, the higher the oven temperature,the shorter the time period in the drying zone, and vice versa.

Generally, during drying, the former remains in the drying zone (orprogresses through this zone) for a period of time sufficient to raisethe surface temperature of the layer of elastomeric film-formingcomposition on the former to a maximum temperature between about 25° C.and about 85° C., for example, about 40° C. to about 80° C. If a highersurface temperature is reached, excessive or uneven drying may occur. Inaddition, the elastomeric film-forming composition on the former mayrequire cooling prior to the next dipping step. An additional coolingstep may result in delays or additional costs in the manufacture of theelastomeric film or article.

The surface temperature of the elastomeric film-forming composition onthe former can be measured using the same techniques described abovewith respect to the coagulant layer surface temperature.

The drying or partial drying is required to reduce the water content ofthe elastomeric film-forming composition on the former. The watercontent of the dried or partially dried elastomeric film-formingcomposition is from zero to greater than 22%, such as between 22% and80%, 25% to 75%, 30% to 75% or 25 to 60%. The water content of theelastomeric film-forming composition on the former can be determined bymeasuring the mass of a sample product at the point of completion of thepartial drying step, and then driving off the remaining moisture/liquidin the sample product to obtain the dry mass of the product, anddetermining from these two values the total water content. Thus, if thesingle-layered product at this point in time weighs 100 mg, and thedried product weighs 90 mg, the water content is 10%.

The method of the present invention encompasses the preparation ofsingle-layered or multiple-layered elastomeric films. Therefore, in someembodiments, the method may include step (v), which involves drying andcuring the layered elastomeric film on the former directly after thisstep to prepare a single layered elastomeric film. In other embodiments,the method may include a number of repetitions of optional steps (iii)and (iv) after this step to produce a multiple-layered elastomeric film.

Step (iii) Optionally Dipping the Former Coated with the Dried orPartially Dried Layer of Elastomeric Film Forming Composition into theElastomeric Film Forming Composition to Produce a Further Layer ofElastomeric Film Forming Composition on the Former

The former coated with the dried or partially dried layer of elastomericfilm-forming composition is optionally dipped into an elastomericfilm-forming composition. The composition into which the former isdipped can be the same as or different to the composition used to formthe first layer. The composition may differ with respect to the identity(inclusive of blending ratios and extent of carboxylation level) and/oramount of the elastomer-forming polymer, the identity and/or amount ofany cross-linking agent, the identity and/or amount of other additives,and the total solids content. In some embodiments, the identity of theelastomer-forming polymer in the second composition is the same as thatused in the first composition. In such embodiments, the amount of thecross-linking agent is also typically the same. In other embodiments,the identity of the elastomer-forming polymer of the second compositionis different to that in the first composition. The total solids contentof the second composition may be the same or different to that of thefirst composition. The total solids content will depend in part on thedesired thickness of the second (or further) layer being applied.

The dwell time of the former in the second composition is, for example,between 1 and 90 seconds, such as between 1 and 30 seconds, 5 and 90seconds, 1 and 60 seconds, 5 and 60 seconds, 1 and 20 seconds, 1 and 10seconds, or 2 and 5 seconds.

The temperature of the composition into which the mould is dipped isgenerally within the range of 10° C. to 60° C., such as 10° C. to 50°C., 15° C. to 50° C., 20° C. to 50° C., 25° C. to 50° C., 25° C. to 45°C., 20° C. to 40° C. or 20° C. to 35° C. Preferably, the compositioninto which the former is dipped is constantly cooled with chilled waterand the latex bath temperature is kept between 20° C. to 40° C., 20° C.to 35° C., 20-30° C. or 25-40° C., more preferably at 25° C. In someembodiments, the composition is constantly circulated in the tank toavoid creaming and settling of the chemicals contained in theelastomeric film-forming composition.

Preferably, the surface temperature of the dried or partially driedlayer of elastomeric film-forming composition on the former does notexceed the temperature of the composition for forming an elastomericfilm by more than about 80° C. It has been found by the applicant thatif the surface temperature is more than about 80° C. higher than thetemperature of the composition for forming an elastomeric film,shrinkage of the elastomeric film-forming composition on the former mayoccur. In some embodiments, the surface temperature is lower than thetemperature of the composition for forming an elastomeric film. However,typically, the surface temperature is about 20° C. to 60° C. higher thanthe temperature of the composition for forming an elastomeric film.

Step (iv) Optionally Repeating the Drying or Partial Drying Step (ii)and the Further Dipping Step (iii)

The drying or partial drying step and further dipping steps may berepeated. These steps are suitably repeated at least once, and may berepeated multiple times. For each repeated step, the conditions may bedifferent compared to the original partial drying conditions and dippingconditions for producing the second layer. Thus, as an example, extentof drying, and/or the total solids content of the composition forforming an elastomeric film may differ for each layer.

For each drying step, the layer of elastomeric film-forming compositionon the former is dried or partially dried to reduce the water content ofthe elastomeric film-forming composition such that water content of thepartially dried layer of elastomeric film on the former has a watercontent of from zero to greater than 22%. This water content is measuredby reference to the water content of the entire elastomeric film layeron the mould (that is, the elastomeric film layer formed by multipledipping). When the elastomeric film-forming composition is partiallydried, it may have a water content in excess of 22% by weight, between22% and 80%, for example, to 25% to 75%, 30% to 77% or 25% to 60%.

The drying or partial drying may be conducted using the same type ofdrying technique as described above in relation to step (b), usingconditions necessary to reach a state of complete or partial dryness.

After the final layer of elastomeric film-forming composition has beenapplied to the former, the elastomeric film-forming composition may bedried, rather than partially dried. This final drying step is describedbelow at Step (v).

The drying or partial drying step (ii) and the further dipping step(iii) will be repeated until the film has a sufficient number of layers,where each layer is produced by a separate dipping step. The furtherdipping step may be conducted using the same technique as describedabove in relation to step (a), using conditions necessary to reach asuitable layer of elastomeric film on the former.

The composition into which the former is dipped can be the same as ordifferent to the composition used to form the first layer or thepreceding layer. The composition may differ with respect to the identity(inclusive of blending ratios and extent of carboxylation level) and/oramount of the elastomer-forming polymer, the identity and/or amount ofany cross-linking agent, the identity and/or amount of other additives,and the total solids content. In some embodiments, the identity of theelastomer-forming polymer used in the further dipping step is the sameas that used to form the preceding layer. In such embodiments, theamount of the cross-linking agent is also typically the same. In otherembodiments, the identity of the elastomer-forming polymer used in thefurther dipping step is different to that used to form the precedinglayer. The total solids content of the composition used in the furtherdipping step may be the same or different to that of the compositionused to form the preceding layer. The total solids content will dependin part on the desired thickness of the further layer being applied.

In the case where multiple layered elastomeric films are prepared, atleast one layer of the elastomeric film will be made from an elastomericfilm-forming composition comprising a carboxylic acid- or ester-graftedpolychlorobutadiene and one or more cross-linking agents. The otherlayers of the elastomeric film may be made from an elastomericfilm-forming composition of the invention or an elastomeric film-formingcomposition comprising other elastomers or blends of other elastomers.

The average thickness of each layer is typically between 6% and 90% ofthe final elastomeric film, with some layers (such as the first layer)suitably being between 30 to 70%, or 40 to 65% of the full filmthickness. The average thickness of each layer is dependent on thenumber of layers of composition forming the final elastomeric film. Thefinal elastomeric film can, for example, consist of 1 to 15 layers. Insome embodiments, the elastomeric film consists of 1 to 15 layers, 2 to14 layers, 1 to 13 layers, 2 to 12 layers, 3 to 15 layers, 1 to 11layers, 2 to 10 layers, 3 to 11 layers, 6 to 10 layers, 8 to 12 layers,10 to 15 layers, 1 to 9 layers, 2 to 8 layers, 3 to 7 layers, 4 to 8layers, 1 to 6 layers, 2 to 5 layers, 2 to 6 layers, 3 to 6 layers, 1 to5 layers, 1 to 4 layers, 1 to 3 layers, or 1 to 2 layers.

Generally, although not always, the greater the number of layers in thefilm, the lower the % TSC of the composition for producing eachsubsequent layer. This is to keep the thickness of the multilayer filmto a minimum. After the first layer, the % TSC of the composition usedto produce each subsequent layer may be in the range 5%-50% TSC, such as5-48% TSC, 5-45% TSC, 5-30% TSC, 5-12% TSC, 10-30% TSC, 10-40% TSC,10-50% TSC, or 10-20% TSC.

Each layer can be of approximately equal thickness, or of differingthickness. For example the 1^(st) layer can be 50%, 2nd layer 30%, 3rdlayer 20% for a 3-layer film. Approximately equal thickness can beachieved by varying the total solids content of the composition of eachlayer and the temperature at which the layer is deposited. Differentmechanisms of deposition can occur for each layer and differentthicknesses can be deposited even if the % TSC is maintained at the samelevel. Accordingly, varying the % TSC is sometimes required to maintainthe same level of thickness. The thickness of the deposited layers canalso vary according to the concentration of ions in the coagulantsolution, or the amount of any sensitiser present in the composition forproducing the elastomeric film temperature of the composition, anddwelling time of the mould into the composition.

Optional Additional Steps Prior to Drying and Curing

Further steps can be taken to fine-tune the manufacture of theelastomeric film or article. The film or article can be leached toremove extractable components. Suitable conditions for leachingextractable components from the film or article can involve contactingthe film or article with heated water (e.g. through immersion) at atemperature between ambient temperature to 80° C., such as 40 to 80° C.or ambient temperature to 55° C. Leaching may be conducted for a timeperiod of between 1 to 50 mins. During this leaching process, asubstantial amount of soluble and extractable components (such assurfactant, ionic compounds) can be removed. Then leached film maysubsequently be dipped into an acrylate/acrylic/urethane polymer (orother suitable coating material) solution. The purpose of this coatingis to make the donning side of the article tack free. Preferably, thestrength of the acrylate/acrylic/ureathane polymer (or other suitablecoating material) solution is about 1-10% w/w.

In the case of glove manufacture, the glove can be subjected tobeading/cuffing to create a bead or cuff at the wrist end of the glove.The beaded glove may then pass through a set of long vulcanizing ovenswith various temperature zones to evaporate the water in the film andenable better cross linking. Preferably, the temperature zones aremaintained at 100-150° C. Vulcanization may be conducted for a timeperiod of between 1 to 50 minutes, or about 15 to 30 minutes dependingon the film thickness.

Step (v) Drying and Curing the Layered Elastomeric Film on the Former

After the required number of layers of film have been added by one ormore iterations of dipping and drying or partial drying steps, the filmor article is then dried and cured.

This step can be effected in an oven with a minimum temperature of 80°C., in the range 80-150° C., such as or 80-120° C., or a minimumtemperature of 90° C. (such as 90-150° C. or 90-120° C.) at a minimumtime of 10 minutes, in the range 10-60 minutes or about 15 to 120minutes. Other drying and curing techniques that can be used includes UVcuring. In the case of glove manufacture, the resulting glove may betumbled using hot air at a temperature of around 40-120° C. for about 10to 120 minutes.

Optional Additional Steps Following Drying and Curing

The film or article is stripped from the former at the conclusion of theformation process.

The film or article can be subjected to one or more further processsteps prior to stripping of the film or article from the former. Theseoptional steps include cooling, chlorination, post-curing rinsing,polymer coating, powder coating and additional drying steps.

In some embodiments, a chlorination step is used to cap the polymersand/or to decrease the tackiness of the film or article. In theseembodiments, the film or article can be chlorinated on line in achlorination chamber. A solution of 200-1500 ppm of free chlorine, or800-1000 ppm of free chlorine may be used. The chlorination process maybe carried out over a period of between about 20-60 seconds, or forabout 25 seconds. The longer the chlorination process, the lower theconcentration of chlorine required in the chlorination process. Thechlorinated film will typically be neutralized and washed before beingdried, cured and vulcanized.

The cured film may also be post-leached in hot water and optionallydipped in lubricant solution or any silicone free polymers to enableeasy stripping and better donning. For surgical gloves or otherspecialty gloves which require specific attributes with respect todonning post processing, further specific steps may be required.

It will be appreciated that minor alteration could be made to the aboveto achieve the required results in terms of film quality, donning,colour, physical property and other quality characteristics etc.

Dipped Articles and Use of the Elastomeric Film-Forming Composition

The elastomeric film-forming composition of the present invention can beused to prepare a variety of dipped articles. Examples of possibledipped articles include surgical gloves and medical examination gloves,industrial gloves, finger cots, catheters, tubing, protective coverings,balloons for catheters, condoms and the like. Preferably, theelastomeric film-forming composition is used in the manufacture ofgloves, such as powder-free gloves.

The thickness of the final film (or article) can, for example, be in therange 0.01-3.0 mm, such as 0.01-2.5 mm, 0.01-2.0 mm, 0.01-1.5 mm,0.01-1.0 mm, 0.01-0.5 mm, 0.01-0.4 mm, 0.01-0.3 mm, 0.01-0.2 mm,0.02-0.2 mm, 0.01-0.10 mm, 0.03-3.0 mm, 0.03-2.5 mm, 0.03-2.0 mm,0.03-1.5 mm, 0.03-1.0 mm, 0.03-0.5 mm, 0.03-0.4 mm, 0.03-0.3 mm,0.03-0.2 mm, 0.03-0.10 mm, 0.05-3.0 mm, 0.05-2.5 mm, 0.05-2.0 mm,0.05-1.5 mm, 0.05-1.0 mm, 0.05-0.5 mm, 0.05-0.4 mm, 0.05-0.3 mm,0.05-0.2 mm, 0.05-0.10 mm, 0.08-3.0 mm, 0.08-2.5 mm, 0.08-2.0 mm,0.08-1.5 mm, 0.08-1.0 mm, 0.08-0.5 mm, 0.08-0.4 mm, 0.08-0.3 mm,0.08-0.2 mm, 0.08-0.10 mm, 0.1-3.0 mm, 0.1-2.5 mm, 0.1-2.0 mm, 0.1-1.5mm, 0.1-1.0 mm, 0.1-0.5 mm, 0.1-0.4 mm, 0.1-0.3 mm, 0.1-0.2 mm, 0.15-3.0mm, 0.15-2.5 mm, 0.15-2.0 mm, 0.15-1.5 mm, 0.15-1.0 mm, 0.15-0.5 mm,0.15-0.4 mm, 0.15-0.3 mm, 0.15-0.2 mm, 0.02-0.08 mm, 0.03-0.08 mm, or0.05-0.08 mm. In some embodiments, the thickness of the final film (orarticle) can, for example, be in the range 0.05-0.08 mm for thin ordisposable gloves, and in the range 0.1-3.0 mm for thick gloves.

In some embodiments, thick films are made of multiple thin layers offilm to reach the desired thickness.

The thickness is suitably measured as an “average thickness”,particularly for gloves, using the points of measurement describedbelow. In some embodiments, the film thickness of a glove is less than 2mm (e.g. from 0.01 mm to 2 mm). For example, the film thickness may bein the range of from 0.04 mm to 2 mm.

In another embodiment, the glove may have a weight of about 4 g, whileit will be appreciated that higher and lower glove weights may also beobtained depending on the purpose for which the glove is to be used.

The final film (or article) can, for example, have one layer or be madefrom multiple layers produced by separate dipping steps. For example,the final film (or article) may comprise from 1 to 15 layers.

The final film prepared from the elastomeric film-forming composition ofthe invention retains the favourable feel and comfort that is closer tonatural rubber film yet is free of proteins and other potentialallergens (causing Type I allergy) associated with natural rubber. Insome embodiments, the final film prepared from the elastomericfilm-forming composition of the invention has reduced skin irritationcompared to natural rubber film. For example, the final film preparedfrom the elastomeric film-forming composition of the invention reducesthe risk of Type I allergy compared to natural rubber film. Preferably,the film prepared from the elastomeric film-forming composition of theinvention avoids Type I allergy.

Where the dipped article is a glove, retaining the properties of naturalrubber gloves also means that the products are easily donnable withoutany visible powder anti tack material. Like natural rubber gloves, thegloves of the present invention could be easily donnable without anyvisible powder anti tack material like talc, corn starch or calciumcarbonate. In some embodiments, the gloves of the present inventioncould have a coating applied on the interior surface of the gloves, suchas a polymeric laminate of acrylate or a powder to assist users indonning the gloves. Further, proper curing of the film removestackiness, and the bonding characteristics of the carboxylic acid- orester-grafted polychlorobutadiene makes the common coating materialsufficient enough for proper donning and non-tacky effect and suitablepowder free conditions. In addition, the presence of chlorine in polymerused in the elastomeric film-forming composition of the presentinvention acts as microbial inhibitor.

The dipped articles prepared from the elastomeric film-formingcomposition of the invention also possess improved physical properties.In some embodiments, the dipped articles prepared from the elastomericfilm-forming composition of the invention have a higher tensilestrength, a lower modulus at 300% and/or a lower modulus at 500% and ahigher elongation to break when compared to other elastomeric to form adipped articles or gloves. In some embodiments, the dipped articlesprepared from the elastomeric film-forming composition of the inventionhave a tensile strength of greater than or equal to about 2000 psi, amodulus at 300% of about 100 to 2000 psi, a stress at 500% of about 200to 3000 psi, and/or an elongation to break of about 400 to 1500%. Forexample, the elastomeric film prepared from the composition of thepresent invention has a tensile strength of at least about 2100 psi, amodulus at 300% of less than 660 psi, a stress at 500% of less thanabout 2400 psi (preferably, the stress at 500% is from about 200 psi to1015 psi), and/or an elongation to break about 400 to 1100%. In someembodiments, the elastomeric film prepared from the composition of thepresent invention has a tensile strength of 2100 psi to 4000 psi, 2200psi to 4000 psi or 2500 psi to 4000 psi. In some embodiments, theelastomeric film prepared from the composition of the present inventionhas a stress at 500% of 200 psi to 2400 psi, 200 psi to 1015 psi, 200psi to 800 psi or 200 psi to 400 psi. In some embodiments, theelastomeric film prepared from the composition of the present inventionhas an elongation to break of greater than 520%. Preferably, theelastomeric film prepared from the composition of the present inventionhas an elongation to break of 520% to 1100%, greater than 650%, 650% to1100%, 750% to 1100%, 800% to 1100%, 900% to 1100% or greater than1000%.

The elastomeric film-forming composition of the invention can be used toform elastomeric films or dipped articles in which the softness of thefilm ranges from very soft to medium to very rigid by varying theamounts of the components used in the composition and the type ofcomponents used in the composition. In some embodiments, the softness ofthe elastomeric film or dipped article can be varied by adjusting thelevel of carboxylation of the polymer/copolymer, the amount and type ofthe second elastomer used in the composition, the amount and type ofcross-linking agent or agents, and/or the amount of chlorine in thepolymer/copolymer. As one example, the elastomeric film prepared fromthe composition of the present invention may be used to form a soft filmhaving a tensile strength of greater than or equal to about 2100 psi, amodulus at 300% of less than or equal to about 660 psi, a stress at 500%of less than or equal to about 1015 psi, and/or an elongation to breakof greater than about 800%. As another example, the elastomeric filmprepared from the composition of the present invention may be used toform a soft to medium film having a tensile strength of greater than orequal to about 2100 psi, a modulus at 300% of less than or equal toabout 1200 psi, a stress at 500% of less than or equal to about 2800psi, and/or an elongation to break of about 500 to 800%. As a furtherexample, the elastomeric film prepared from the composition of thepresent invention may be used to form a medium to rigid film having atensile strength of greater than or equal to about 2100 psi, a modulusat 300% of less than about 1200 psi, a stress at 500% of less than about2800 psi, and/or an elongation to break of about 400 to 700%.

The properties of the elastomeric film will be determined in part by thelevel of carboxylation of the carboxylic acid- or ester graftedpolychlorobutadiene, and the amount of blending with the one or moresecond elastomers, and therefore, these features can be adjusted toarrive at the desired elastomeric film. This improvement may be evenbetter when using the combination of an ionic cross-linking agent (forexample a metal oxide or a metal hydroxide) and a covalent cross-linkingagent (for example sulphur or a sulphur-containing vulcanising agent) asthe cross-linking agents with the carboxylic acid- or ester graftedpolychlorobutadiene.

For example, thinner, softer and more elastic films are produced whenthe carboxylic acid or ester content is in the range of about 0.01 to5.0%, or the chlorine content is in the range of about 10 to 50%. Morerigid, less elastic or more durable films are produced when thecarboxylic acid or ester content is in the range of about 0.5 to 8% orthe chlorine content is in the range of about 30 to 58%. When a secondelastomer is used in the composition, the amount that is used willdepend on the carboxylic acid or ester content and the chlorine contentof the carboxylic acid- or ester-grafted polychlorobutadiene and theproperties required for the resulting elastomeric film or dippedarticle. The amount of the second elastomer is expressed as a percentageof the polymer component of the composition on a dry basis and may beselected from within one of the following ranges: 0 to 95%, 5-95%,0-75%, 0-65%, 5-75%, 5-65%, 10-95%, 10-75%, 10-65%, 16-95%, 15-75%,15-65%, 20-95%, 20-75%, 20-65%, 25-95%, 25-75%, 25-65%, 30-95%, 30-75%,30-65%, 35-95%, 35-75%, 35-65%, 40-95%, 40-75%, 40-65%. It will beappreciated that a blended composition will retain the favourableproperties provided by the use of the carboxylic acid- or ester-graftedpolychlorobutadiene. Preferably, the amount of the second elastomer isless than about 75%, such as 0-75%, 5-75%, 10-75%, 15-75%, 20-75%,25-75%, 30-75%, 35-75% or 40-75%.

The desired durability of the film is determined by the end use of thearticle. For example, for gloves for non-surgical use, the wearing timeis usually below 3 hrs, and commonly less than 2 hrs. The durability ofthe film can be controlled by the curing conditions. Generally, thehigher the curing temperature, the more durable the elastomeric film.

The term “average thickness” in respect of the thickness of a glove(specifically the multi-layer elastomeric film forming the glove) refersto the average of three thickness measurements, taken at points alongthe layer of the elastomeric film. The measurements are taken at thecuff, the palm and the finger tip. When measuring the thickness ofindividual layers of the glove, the “average thickness” is a referenceto the average thickness of that layer of film, taken at the threemeasurement points. This may be measured in absolute terms (in mm), oras a percentage of the full thickness of the multi-layered glove. Forelastomeric articles, a similar technique using three thicknessmeasurements can be used to determine the “average thickness”.

In the claims and in the preceding description, except where the contextrequires otherwise due to express language or necessary implication, theword “comprise” or variations such as “comprises” or “comprising” isused in an inclusive sense, i.e. to specify the presence of the statedfeatures but not to preclude the presence or addition of furtherfeatures in various embodiments of the invention.

The invention is illustrated by the following examples. It is understoodthat one of ordinary skill in the art will understand how to vary thetimes and temperature of the process in accord with the articlemanufactured, the specific carboxylated polychloroprene copolymer orblend employed, the particular formulation ingredients selected withrespect to the carboxylation level of the latex concerned.

EXAMPLES

The invention will now be described in further detail with reference tothe following non-limiting examples. All testing procedures are shown inthe Testing Procedures section, and the results of these tests areshown. All tables of compositions and test results are shown in theTables section.

General Procedure

In the examples set out below, the following general procedure wasutilised to produce elastomeric films, and gloves in particular. Thegeneral procedure was also used to demonstrate the impact (if any) thatcertain processing conditions and components of the elastomeric filmforming compositions have on the quality of multilayer elastomeric filmsproduced.

The following general procedure was followed for the all the Examples(1-10) described below.

1. Washing

The formers are subjected to pre-washing, so as to be clean of anyremaining residues following removal of a glove previously made on theformer. The formers are cleaned in mild acid/alkali and hot water. Theformers are then dried by blowing air by blowers or air curtains orusing ovens with the hot air having temperature above 105° C.

2. Coagulant Dipping

The cleaned dry former is immersed in the coagulant bath, which containsa 0-50% by weight solution of calcium nitrate. The coagulant alsocontains 0.1%-5.0% by weight metallic stearates, suitable wetting agents(0.001-1.0%) and antifoaming agents (0.001-1.0%).

3. Drying

The coagulant coated formers are dried in a hot air circulated oven at atemperature of about 110° C. to 130° C.

4. First Dipping Step

The former, coated with dried coagulant, is dipped into a tank of thecomposition for forming an elastomeric film, which contains thecomponents specified for the given example. The composition used has aconcentration of about 5 to 60% by weight, and preferably 10-40% byweight. The composition is maintained at temperature of around 20-35°C., and is constantly circulated in the tank to avoid creaming andsettling of chemicals. The former is dipped into the composition for adwell time of 5 seconds to 60 seconds.

5. Drying

The composition coated formers are gelled in a gelling oven at atemperature of about 100-300° C. and the duration of 2-300 seconds.

6. Pre-Leaching

Pre-leaching is conducted by rinsing in warm water for a short period oftime. The gelled film coating on the former is pre-leached in series oftanks at ambient temperature to 55° C.

7. Second Dipping Step

Then pre-leached gelled film coating on the former is dipped into a tankof the composition for forming an elastomeric film, which contains thecomponents specified for the given example. The composition has aconcentration of about 5 to 50%, and preferably 8-35% by weight. Thecomposition is maintained at temperature of around 10-60° C., andpreferably 20-40° C., and is constantly circulated in the tank to avoidcreaming and settling of chemicals. The former is dipped into thecomposition for a dwell time of 5-90 seconds.

8. Gelling/Pre Leaching/Beading

The product following the second dipping step is subjected to gellingand pre-leaching and beading.

The beading, drying and pre-leaching steps could be carried out in anyorder. The processes of beading and pre-cure leaching could be exchangedepending on the quality of cuff beading.

9. Vulcanization

The beaded glove is then vulcanized at about 100° C.-150° C. for about15-30 minutes depending upon the film thickness.

10. Post-Leaching/Lubricant/Final Drying/Stripping/Tumbling

The vulcanized glove will be post leached and lubricant dipped(optional) and stripped after final drying. Where additional curing orsurface treatment is required, the gloves could be tumbled using hot airat a temperature around 40-120° C. for about 10-120 minutes.

General Formulation

The generic glove formulation is as follows:

TABLE 1 Parts per Hundred Rubber Ingredients (phr) - Dry basisCarboxylic acid- or ester-grafted 100-5  polychloroprene Latex* orblend** Second elastomer  0-95 Plasticizer stabilizer 0.5-5.0 Emulsifierstabilizers 0.5-5.0 Antiozonant 0.5-5.0 pH stabilizer 0.1-1.5Vulcanization activator 0.5-8.0 Cross-linker 0.5-3.0 Vulcanizingaccelerator 0.5-4.0 Antioxidant 0.5-3.0 Opaqueness provider 0.01-3.0 Pigment As per requirement Defoamer 0.001-2.0  *The carboxylic acidcontent is important. The effect of carboxylic content on the propertiesof the elastomeric film is discussed in further detail below.**Commercially available second elastomers, such as Synthomer Type X3000used in Examples 3 to 10 are often supplied in the form of acarboxylated nitrile butadiene rubber.

In addition to the General Formulation provided above, it will beappreciated that the following components may also be added to theformulation as necessary.

-   -   The pH stabilizers may be for example oleates, stearates or        other non-ionic surfactants or potassium hydroxide, ammonium        hydroxide and or sodium hydroxide.    -   The suitable emulsifier stabilizers may be sodium alkyl        sulphates, potassium salts of resin/rosin acids or other        non-ionic surfactants.    -   The antiozonants used may be paraffinic waxes, microcrystalline        waxes and intermediate types. The vulcanization activator of        metal oxides may be magnesium oxide or zinc oxide.    -   The cross-linker may be sulphur and/or other organic peroxides        and/or cross linkable reactive monomers.    -   The vulcanization accelerators is chosen from        mercaptobenzothiazoles and derivatives, dithiocarbamates and        derivatives, sulphur donors, guanidines and its derivatives,        thiourea and its derivatives and aldehyde amine reaction        products.    -   The antioxidant may be hindered polymeric phenols or arylamines.        Opaqueness provider could be titanium oxide or other minerals.    -   Defoamer may be naphthalene type defoamers, vegetable oil based        defoamers, silicone type defoamers and like.

Carboxylic Acid or Ester Grafting of Polychlorobutadiene

The carboxylate- or ester-grafted polychlorobutadiene may be preparedusing one of the various methods described in “Polymer Grafting andCross-linking” Edited by Dr. Amit Bhattacharya, Dr. James W. Rawlins,and Dr. Paramita Ray, John Wiley & Sons, Inc., 2009, and in “Grafting: aversatile means to modify polymers: Techniques, factors andapplications” Bhattacharyaa, A. and Misrab, B. N., Progress in PolymerScience, 2004, Volume 29, Issue 8, pages 767-814, the contents of whichare incorporated herein by reference.

As one example, the carboxylate- or ester-grafted polychlorobutadienemay be prepared using the following general procedure.

A first solution containing 92-99 parts poly-2-chloro-1,3-butadiene, 1-8parts methacrylic acid and 0.8 parts diisopropyl xanthogen disulfide isprepared. A second solution containing 3-8 parts polyvinyl alcohol (PVA)in water was also prepared. The first and second solutions wereemulsified to form an oil-in-water emulsion. An amount of 90-100 partsof water was used. The redox catalyst system used was sodium sulfite andpotassium persulfate, which were added as required to initiate andmaintain grafting. The reaction was carried out at a temperature of 45°C. to full conversion (about 98 percent). At the end of the reaction, anemulsion containing about 0.01 part each of phenothiazine and4-tertbutylpyrocatechol was added to stabilize against any furtherreaction The general procedure was used to prepare the elastomeric filmforming compositions for the all the Examples (1-10) described below.

In order to produce carboxylic acid-grafted polychloroprene havinglevels of carboxylation of 0.01%, 1.5% and 2.5%, the method wascontrolled by adjusting the amount of carboxylic acid or ester usedrelative to the amount of polychlorobutadiene used. For 100 kg ofpoly-2-chloro-1,3-butadiene, the amount of methacrylic acid used was0.02 kg, 2.925 kg and 4.875 kg, respectively (calculated at 98%conversion). The amounts of carboxylic acid or ester (or the extent ofgrafting or the degree of carboxylation of the polymer) may be verifiedby determining the amount of unreacted carboxylic acid or ester usinganalytical methods, and subtracting this amount from the amount ofcarboxylic acid or ester added.

Example 1

This Example demonstrates that single or multi-layer gloves (1-15layers) can be made using the General Procedure outlined above. Thegloves were made using the composition outlined in Table 2 below. Inthis Example, the carboxylic acid grafted polychloroprene copolymer(CPC) was prepared as described above, having a carboxylation level of1.5%.

TABLE 2 Example 1 Carboxylic acid-grafted polychloroprene* 100 ZincOxide 1.8 Sulphur 0.6 Accelerator ZDBC 0.6 TiO₂ 1.0 Anti oxidant 0.6 Wax0.5 Pigment 0.05 Surfactant 0.5 pH stabilizer 0.3 Anti foam 0.005 *Levelof carboxylation = 1.5%

The glove produced using the above formulation and conditions statedearlier was soft and felt like glove made out of natural polyisoprenematerial. However the modulus and elongation were better than glove madeof natural polyisoprene. The film was uniform and no weak spot or pinholes noticed. The glove thickness varied from 0.05 to 0.11 from cuffend to the finger tip.

Example 2

This Example demonstrates that single or multi-layer gloves (1-15layers) can be made when using a different composition to that used inExample 1 above. In this Example, the carboxylic acid-graftedpolychloroprene (CPC) copolymer was prepared as described above, havinga carboxylation level of 2.5%. The gloves were made using the GeneralProcedure, and using the composition outlined in Table 3 below.

TABLE 3 Example 2 Carboxylic acid-grafted polychloroprene* 100 ZincOxide 1.8 Sulphur 0.6 ZDBC 0.6 TiO₂ 1.0 Anti oxidant 0.6 Wax 0.5 Pigment0.05 Surfactant 0.5 pH stabilizer 0.3 Anti foam 0.005 *Level ofCarboxylation - 2.5%

The glove produced using the above formulation and conditions statedearlier was soft and felt like glove made out of natural polyisoprenematerial. The modulus and elongation were almost equal to that of glovemade of natural polyisoprene. The film was uniform and no weak spot orpin holes were observed. The glove thickness varied from 0.05 to 0.10from cuff end to the finger tip. The modulus of the glove was found tobe higher than the gloves of Example 1 which could be due to the highercarboxylation level (2.5% against 1.5% of Example 1).

Example 3

This Example demonstrates that single or multi-layer gloves (1-15layers) can be made when using a different composition to that used inExample 1 above. In this Example, the polymer used was CPCB (acarboxylic acid-grafted polychloroprene blend). The blend consists of15% maximum of nitrile butadiene rubber latex (this Example usedSynthomer Type X3000 which is commercially available from Synthomer,Nippon Zeon, Khumho, LG, NanTex or other material of near equivalentspecifications may be used). The carboxylic acid-grafted polychloroprenewas prepared as described above, having a carboxylation level of 1.5%.The composition also included higher amounts of cross-linking agentssuch as zinc oxide, sulphur and ZDBC, and a higher amount of theantioxidant. The gloves were made using the General Procedure, and usingthe composition outlined in Table 4 below.

TABLE 4 EXAMPLE 3 Carboxylic acid-grafted polychloroprene * 85 Nitrilebutadiene rubber latex 15 Zinc Oxide 5 Sulphur 1 Curative ZDBC 1Titanium dioxide 1 Surfactant 0.5 Wax 0.5 Anti Oxidant 1 Pigment 0.05 pHstabilizer 0.3 Anti foam 0.005 * Level of Carboxylation - 1.5%

The film was uniform and no weak spot or pin holes were observed. Theglove thickness varied from 0.05 to 0.10 from cuff end to the fingertip. The modulus of the glove was found to be higher than the gloves ofExample 2 which could be due to blending with nitrile butadiene rubberlatex, however, the elongation was better than typical nitrile butadienerubber products.

Example 4

This Example demonstrates that single or multi-layer gloves (1-15layers) can be made when using a different composition to that used inExample 1 above. In this Example, the polymer used was CPCB (acarboxylic acid-grafted polychloroprene blend). The blend consists of15% maximum of nitrile butadiene rubber latex (this Example usedSynthomer Type X3000 which is commercially available from Synthomer,Nippon Zeon, Khumho, LG, NanTex or other material of near equivalentspecifications may be used). The carboxylic acid-grafted polychloroprenewas prepared as described above, having a carboxylation level of 2.5%.The composition also included higher amounts of cross-linking agentssuch as zinc oxide, sulphur and ZDBC, and a higher amount of theantioxidant. The gloves were made using the General Procedure, and usingthe composition outlined in Table 5 below.

TABLE 5 EXAMPLE 4 Carboxylic acid-grafted polychloroprene * 85 Nitrilebutadiene rubber latex 15 Zinc Oxide 5 Sulphur 1 Curative ZDBC 1Titanium dioxide 1 Surfactant 0.5 Wax 0.5 Anti Oxidant 1 Pigment 0.05 pHstabilizer 0.3 Anti foam 0.005 * Level of Carboxylation - 2.5%

The film was uniform and no weak spot or pin holes were observed. Theglove thickness varied from 0.05 to 0.10 from cuff end to the fingertip. The glove found to be tougher and modulus of the glove was found tobe higher than the gloves of Example 3 which could be due to blendingwith nitrile butadiene rubber latex and/or the higher carboxylationlevel of the base polymer, however, the elongation was better thantypical nitrile butadiene rubber products.

Example 5

This Example demonstrates that single or multi-layer gloves (1-15layers) can be made when using a different composition to that used inExample 1 above. In this Example, the polymer used was CPCB (acarboxylic acid-grafted polychloroprene blend). The blend consists of15% maximum of nitrile butadiene rubber latex (this Example usedSynthomer Type X3000 which is commercially available from Synthomer,Nippon Zeon, Khumho, LG, NanTex or other material of near equivalentspecifications may be used). The carboxylic acid-grafted polychloroprenewas prepared as described above, having a carboxylation level of 1.5%.The composition also included lower amounts of cross-linking agents suchas zinc oxide, sulphur and ZDBC, and the same amount of the antioxidantas used in Examples 3 and 4. The gloves were made using the GeneralProcedure, and using the composition outlined in Table 6 below.

TABLE 6 EXAMPLE 5 Carboxylic acid-grafted polychloroprene * 85 Nitrilebutadiene rubber latex 15 Zinc Oxide 2.5 Sulphur 0.5 Curative ZDBC 0.5Titanium dioxide 1 Surfactant 0.5 Wax 0.5 Anti Oxidant 1 Pigment 0.05 pHstabilizer 0.3 Anti foam 0.005 * Level of Carboxylation - 1.5%

The film was uniform and no weak spot or pin holes were observed. Theglove thickness varied from 0.05 to 0.11 from cuff end to the fingertip. The glove found to be better and modulus of the glove was found tobe lower than the gloves of Example 4 which could be due to the use of alower level of chemicals, however the elongation was much better thantypical nitrile butadiene rubber products.

Example 6

This Example demonstrates that single or multi-layer gloves (1-15layers) can be made when using a different composition to that used inExample 1 above. In this Example, the polymer used was CPCB (acarboxylic acid-grafted polychloroprene blend). The blend consists of15% maximum of nitrile butadiene rubber latex (this Example usedSynthomer Type X3000 which is commercially available from Synthomer,Nippon Zeon, Khumho, LG, NanTex or other material of near equivalentspecifications may be used). The carboxylic acid-grafted polychloroprenewas prepared as described above, having a carboxylation level of 2.5%.The composition also included lower amounts of cross-linking agents suchas zinc oxide, sulphur and ZDBC, and the same amount of the antioxidantas used in Examples 3 and 4. The gloves were made using the GeneralProcedure, and using the composition outlined in Table 7 below.

TABLE 7 EXAMPLE 6 Carboxylic acid-grafted polychloroprene * 85 Nitrilebutadiene rubber latex 15 Zinc Oxide 2.5 Sulphur 0.5 Curative ZDBC 0.5Titanium dioxide 1 Surfactant 0.5 Wax 0.5 Anti Oxidant 1 Pigment 0.05 pHstabilizer 0.3 Anti foam 0.005 * Level of Carboxylation - 2.5%

The film was uniform and no weak spot or pin holes were observed. Theglove thickness varied from 0.05 to 0.10 from cuff end to the fingertip. The glove found to be tougher and modulus of the glove was found tobe higher than the gloves of Example 5 which could be due to highercarboxylation level of the base polymer, however, the elongation wasbetter than typical nitrile butadiene rubber products. The strength ofthe gloves is better than the gloves of Example 4, where a higher levelof chemicals and an equal carboxylation and blending ratio was used.

Examples 7 to 10 Experiment to Validate the Lower Limit of Carboxylationand Higher Limit of Blending

In this example the validation is performed for 0.01% carboxylation andblending the composition with low cost film forming latex in amounts ofup to 95%.

0.01% carboxylation was kept constant and the blending conditions weretaken in stages of 30%, 45%, 75% and 95%.

These Examples demonstrate that single or multi-layer gloves (1-15layers) can be made when using a different composition given in thetable below. In these Examples, the polymer used was CPCB (a carboxylicacid-grafted polychloroprene blend). The blend consists of up to 95% ofnitrile butadiene rubber latex (these Examples used Synthomer Type X3000which is commercially available from Synthomer, Nippon Zeon, Khumho, LG,NanTex or other material of near equivalent specifications may be used).The carboxylic acid-grafted polychloroprene was prepared as describedabove, having a carboxylation level of 0.01%. The composition alsoincluded cross-linking agents such as zinc oxide, sulphur and ZDBC, andantioxidant as given in the table below. The gloves were made using theGeneral Procedure, and using the composition outlined in Table 8 below.

TABLE 8 Example 7 8 9 10 Carboxylic acid-grafted 25 55 70 5polychloroprene* Nitrile Butadiene Rubber 75 45 30 95 Zinc Oxide 2 3 41.2 Sulphur 1.5 1.5 1.5 1.5 Curative ZDBC 1.0 1.25 1.50 0.8 Titaniumdioxide 2 2 2 2 Surfactant 0.5 0.5 0.5 0.5 Wax 0.5 0.5 0.5 0.5 AntiOxidant 1 1 1 1 Pigment 0.05 0.05 0.05 0.05 pH stabilizer 0.3 0.3 0.30.3 Antifoam 0.005 0.005 0.005 0.005 *Level of Carboxylation - 0.01%

The gloves made from the above compositions had a uniform film and noweak spots or pin holes were observed. The glove thickness varied from0.05 to 0.10 from cuff end to the finger tip.

Example 7

The resulting glove was tough and almost like nitrile gloves withminimal elasticity. However, it is still better than the regular nitrilegloves by feel and softness due to the presence of carboxylatedpolychlroroprene.

Example 8

The gloves produced were softer than the gloves of Example 7

Example 9

The resulting glove was soft and had a stretchability that was betterthan the gloves of Examples 7 and 8.

Example 10

The resulting glove was tough and almost like nitrile gloves withminimal elasticity. Such gloves may be suitable for low costapplications where comfort is not a crucial factor. However, it will beappreciated that the formulation could be further modified by reducingthe amount or type of cross-linking agents to make a softer and/or morestretchable glove.

Test Procedures

For all of the Examples, the following testing techniques were used.

General Testing Procedures

Tensile strength, stress at 300% and 500% modulus and elongation tobreak were measured by testing procedures conducted in accordance withASTM D 412-06a (2013). This standard is available from ASTMInternational, and details the standard specifications and testingstandards used for testing vulcanized rubber and Thermoplasticelastomers. These tests can be applied to multilayer films and gloves(such as examination and surgical gloves for medical applications).

Results

The elastomeric films prepared using the elastomeric film-formingcompositions of Examples 1 to 6 were tested, and the followingproperties of the elastomeric films were measured:

-   -   Modulus at 300%    -   Modulus at 500%    -   Tensile strength (Psi); and    -   Elongation %.

The results of these measurements are shown in Table 9.

TABLE 9 Example 1 2 3 4 5 6 % 1.5 2.5 1.5 2.5 1.5 2.5 CarboxylationPolymer# CPC CPC CPCB CPCB CPCB CPCB Curatives* Low Low High High LowLow Modulus at 150 270 430 605 390 550 300% Modulus at 220 350 840 890650 835 500% Tensile 2900 3050 2830 2900 2925 3145 strength PsiElongation % 1050 925 785 760 820 775 #CPC refers to a carboxylicacid-grafted polychloroprene having the specified % carboxylation. CPCBrefers to a blend containing a carboxylic acid-grafted polychloroprenehaving the specified % carboxylation and a second elastomer as describedin Examples 3 to 6 above.

TABLE 10 Example 7 8 9 10 % Carboxylation 0.01 0.01 0.01 0.01 CPC# phr25 55 70 5 Nitrile Butadiene Rubber phr 75 45 30 95 Modulus at 300% 610335 330 650 Modulus at 500% 2030 800 730 2320 Tensile strength Psi 31902320 2180 3340 Elongation % 550 630 700 530 #CPC refers to a carboxylicacid-grafted polychloroprene having the specified % carboxylation.

By comparing the values obtained for each of these compositions, thefollowing general conclusions can be made:

1. The lower the degree of carboxylation of the polymer, the higher theelasticity of the film. As shown in Table 9 above, the elongation % ishigher in Examples 1, 3 and 5 which used a polymer having acarboxylation level of 1.5% when compared with Examples 2, 4 and 6 whichused a polymer having a carboxylation level of 2.5%. It follows that thehigher the carboxylation level, the higher the modulus at 300%, themodulus at 500%, and the tensile strength, but the film will have alower elongation %.2. The lower the degree of carboxylation of the polymer, the lower themodulus of the film. As shown in Table 9 above, the modulus is lower inExamples 1, 3 and 5 which used a polymer having a carboxylation level of1.5% when compared with Examples 2, 4 and 6 which used a polymer havinga carboxylation level of 2.5%.3. The higher level of cross-linking agents used in Examples 3 and 4does not have significant effect on tensile strength than the lowerlevel of cross-linking agents used in Examples 5 and 6. However, themodulus values for Examples 3 and 4 are marginally higher and theelongation is marginally lower when compared to Examples 5 and 6. Thisresult suggests that increased amounts of cross-linking agents does nothave much impact.4. By comparison of the modulus values of Examples 1 and 2 against themodulus values of Examples 3-6, it can be found that when the carboxylicacid-grafted polychloroprene is used, the modulus of the elastomericfilm is lower than when the blend containing a carboxylic acid-graftedpolychloroprene is used. However, it will be appreciated that articlesprepared using the blend containing a carboxylic acid-graftedpolychloroprene could be used in selected applications.5. Examples 5 and 6 were made with equal levels of crosslinking agents(2.5 phr ZnO, 0.5 phr sulphur and 0.5 phr ZDBC) with the blending ratioof 15% by weight. However the carboxylation levels of Examples 5 and 6were 1.5 and 2.5%, respectively. It is evident from FIG. 1, that evenwith limited blending (i.e. a lower amount of the second elastomer), ahigher carboxylation level results in a higher modulus at 300%, modulusat 500%, and tensile strength, but a lower elongation %.6. The total % chemical consumption in Examples 1 & 2 is less whencompared to the conventional curing system used for polychloroprenepolymers. In particular, the total % chemical consumption of metal oxideis only 1.8%, while in the conventional curing system used forpolychloroprene polymers, the total % chemical consumption of metaloxide varies from 6 to 10%, which is approximately 3 to 5 times more. Inaddition, curing could be achieved at 100-130° C. for an oven residencetime of 15-30 minutes. The reduction in the amount of zinc oxide,combined with the temperature and duration required for curing providesnumerous environmental advantages.7. Examples 9, 8, 7 and 10 were made with a carboxylation level of0.01%, however, the amount of the second elastomer is 30, 45, 75 and 95respectively. The ZnO level was 4 phr, 3 phr, 2 phr and 1.2 phr (forExamples 9, 8, 7 and 10, respectively), the sulphur level was 1.5 phr,and the ZDBC level was 1.5 phr, 1.25 phr, 1.0 phr, and 0.8 phr (forExamples 9, 8, 7 and 10, respectively). With the increasing amount ofthe second elastomer, the modulus at 300%, modulus at 500%, and tensilestrength increased, while the elongation % decreased.8. Of Examples 1 to 10, Example 1 gave the lowest modulus (150 psi) andhighest elongation (1050%).

Validating the Limits of Lower Carboxylation Level and Higher Blending(Table 10)

The lowest carboxylation level and highest blending level providesuitable gloves despite that the product is not as soft as those ofExamples 1 to 6.

The gloves of Example 7, 8, 9 and 10 will pass ASTM specification formedical gloves made using polychloroprene material, hence the limits arevalidated to make the gloves.

In the case of examples 7, 8, 9 and 10, it has been found that the glovebecomes softer as the amount of carboxylic acid-grafted polychloroprene(having a percent carboxylation of 0.01) increases, in other words themodulus values and tensile values increase as the amount of carboxylicacid-grafted polychloroprene is reduced and the nitrile butadiene rubbercontent increases. The elongation increases as the amount of carboxylicacid-grafting increases.

The foregoing description and examples relate only to preferredembodiments of the present invention and numerous changes andmodifications may be made therein without departing from the spirit andscope of the invention as defined in the following claims.

It is to be understood that, if any prior art publication is referred toherein, such reference does not constitute an admission that thepublication forms a part of the common general knowledge in the art, inAustralia or any other country.

In the claims which follow and in the preceding description of theinvention, except where the context requires otherwise due to expresslanguage or necessary implication, the word “comprise” or variationssuch as “comprises” or “comprising” is used in an inclusive sense, i.e.to specify the presence of the stated features but not to preclude thepresence or addition of further features in various embodiments of theinvention.

Items

The present invention relates to the following items:

1. An elastomeric film-forming composition comprising:

-   -   a carboxylic acid- or ester-grafted polychlorobutadiene, and    -   one or more cross-linking agents.        2. The composition of item 1, wherein the chlorobutadiene is        selected from the group consisting of 2-chloro-1,3-butadiene,        2,3-dichloro-1,3-butadiene and combinations thereof.        3. The composition of item 1 or 2, wherein the carboxylic acid        or ester is an ethylenically unsaturated carboxylic acid or        ester having the formula:

CR¹H═CR²—C(O)—OR³

or

CR¹H═CR²—O—C(O)—R³

whereinR¹ is hydrogen, an alkyl radical containing 1 to 4 carbon atoms,—C(O)—OR⁴ or —R⁵—C(O)—OH, wherein R⁴ is hydrogen or an alkyl radicalcontaining 1 to 4 carbon atoms and R⁵ is an alkyl radical containing 1to 4 carbon atoms;R² is hydrogen, an alkyl radical containing 1 to 4 carbon atoms, or acarboxymethyl radical;R³ is hydrogen, an alkyl radical containing 1 to 4 carbon atoms, or—R⁶O—C(O)—CR⁷═CR⁸, wherein R⁶ is an alkyl radical containing 1 to 4carbon atoms, and R⁷ and R⁸ are each independently hydrogen or an alkylradical containing 1 to 4 carbon atoms; andcis or trans isomers thereof4. The composition of any one of items 1 to 3, wherein the carboxylicacid or ester is selected from the group consisting of acrylic acid,methacrylic acid, crotonic acid, fumaric acid, maleic acid, citraconicacid, glutaconic acid, vinyl acetate, methyl acrylate, methacrylateester, ethylenediol dimethacrylate, butanediol dimethacrylate,methymethacrylate, butylmethacrylate, glacialmethacrylic acid andcombinations thereof.5. The composition of any one of items 1 to 4, wherein the carboxylicacid- or ester-grafted polychlorobutadiene contains the carboxylic acidor ester in an amount of from 0.01% to 8% by weight of thechlorobutadiene units present in the polymer.6. The composition of any one of items 1 to 5, wherein the polymercomprises from 10 to 60% or 10 to 58% chlorine by weight of thechlorobutadiene units present in the polymer.7. The composition of any one of items 1 to 6, wherein the concentrationof the total solids in the composition is between 5-60% by weight of thecomposition.8. The composition of any one of items 1 to 7, wherein the cross-linkingagent is selected from the group consisting of carbamates,thiocarbamates, thiurams, thiourea, thiazoles, guanidines,aldehyde/amine-based accelerators, ionic cross-linking agents, organicand inorganic metal oxides, organic and inorganic metal hydroxidesorganic and inorganic peroxides, covalent cross-linking agents, sulphur,crosslinking monomers, reactive oligomers, polyisocyanate oligomers,functional crosslinkable polymers; derivatives of ethylene glycoldi(meth)acrylate, derivatives of methylenebisacrylamide,formaldehyde-free crosslinking agents, divinylbenzene, divinylether,diallyl phthalate, divinylsulfone and combinations thereof.9. The composition of item 8, wherein the cross-linking agent comprisesan ionic cross-linking agent and a covalent cross-linking agent.10. The composition according to item 9, wherein the ionic cross-linkingagent is a metal oxide or metal hydroxide.11. The composition according to item 10, wherein the metal oxide ormetal hydroxide is selected from one or a mixture of agents from thegroup consisting of lead oxide, magnesium oxide, barium oxide, zincoxide, manganese oxide, copper oxide, nickel oxide, aluminium oxide,zinc hydroxide, magnesium hydroxide, barium hydroxide, manganesehydroxide, copper hydroxide, aluminium hydroxide and nickel hydroxide.12. The composition according to item 9, wherein the covalentcross-linking agent is sulphur or a sulphur-containing vulcanisingagent.13. The composition according to any one of items 1 to 12, wherein theamount of cross-linking agent in the composition is in the range0.5-15.0 phr, 1.0-15.0 phr, 1.5-15.0 phr, 0.5-13.0 phr, 1.0-13.0 phr,1.5-13.0 phr, 0.5-11.0 phr, 1.0-11.0 phr, 1.5-11.0 phr, 0.5-10.0 phr,1.0-10.0 phr, 1.5-10.0 phr, 0.5-8.0 phr, 1.0-8.0 phr, 1.5-8.0 phr,0.5-7.0 phr, 1.0-7.0 phr, 1.5-7.0 phr, 2.0-8.0 phr, 2.5-10.0 phr,5.0-10.0 phr, 3.0-7.0 phr, 3.0-6.0 phr, 4.0-7.0 phr, 4.0-6.0 phr,4.0-5.0 phr, 2.0-5.0 phr, 2.0-4.0 phr, 3.0-4.0 phr, 0.01-3.5 phr,0.01-3.0 phr, 0.01-2.0 phr, 0.01-1.5 phr, 0.01-1.0 phr or 0.01-0.5 phr.14. The composition of item 10 or 11, wherein the amount of metal oxideor metal hydroxide cross-linking agent in the composition is in therange 1.0-10.0 phr, 2.0-8.0 phr, 2.5-10.0 phr, 5.0-10.0 phr, 3.0-7.0phr, 3.0-6.0 phr, 4.0-7.0 phr, 4.0-6.0 phr, 4.0-5.0 phr, 2.0-5.0 phr,2.0-4.0 phr or 3.0-4.0 phr15. The composition according to item 12, wherein the amount of sulphuror sulphur-containing vulcanising agent in the composition is in therange 0.01-3.5 phr, 0.01-3.0 phr, 0.01-2.0 phr, 0.01-1.5 phr, 0.01-1.0phr or 0.01-0.5 phr.16. The composition of any one of items 1 to 13, wherein the compositionfurther comprises a second elastomer selected from the group consistingof nitrile rubber, styrene butadiene rubber, butyl rubber, polyisoprene,polychloroprene, polybutadiene, polyvinylchloride, polyurethane, styrenediblock copolymers, styrene triblock copolymers, acrylic polymers andmixtures thereof.17. The composition of item 16, wherein the second elastomer iscarboxylated, non-carboxylated or a mixture of carboxylated andnon-carboxylated elastomers.18. The composition of item 16 or 17, wherein the second elastomer ispresent in an amount of 0-95%, 5-95%, 0-75%, 5-75%, 0-65%, 5-65%, 0-50%,5-50%, 10-95%, 10-75%, 10-65%, 15-95%, 15-75%, 15-65%, 20-95%, 20-75%,20-65%, 25-95%, 25-75%, 25-65%, 30-95%, 30-75%, 30-65%, 35-95%, 35-75%,35-65%, 40-95%, 40-75%, 40-65%, 50-95%, 50-75%, 50-60%, 50-65%, 60-65%,60-75%, 60-80%, 60-95%, 70-90%, 70-95%, 80-95%, 1-5%, 5-10%, 10-15%,15-20%, 20-25%, 25-30%, 30-35%, 35-40%, or 40-50% by weight of thepolymer component of the composition.19. A dipped article made from an elastomeric film comprising:

-   -   at least one layer of a cured composition of    -   a carboxylic acid- or ester-grafted polychlorobutadiene, and    -   one or more cross-linking agents.        20. A dipped article made from the elastomeric film-forming        composition of any one of items 1 to 18.        21. The dipped article of item 19 or 20, wherein the article is        a glove.        22. The dipped article of any one of items 19 to 21, wherein the        average thickness of the elastomeric film is between about 0.01        mm to about 3 mm.        23. The dipped article of any one of items 19 to 22, wherein the        elastomeric film comprises from 1 to 15 layers, and each layer        is produced by a separate dipping step.        24. A glove comprising at least one layer of elastomeric film        comprising:    -   a carboxylic acid- or ester-grafted polychlorobutadiene, which        is cross-linked with one or more cross-linking agents.        25. The glove of item 24, having a tensile strength of greater        than or equal to about 2000 psi, a modulus at 300% of about 100        to 2000 psi, a stress at 500% of about 200 to 3000 psi, and/or        an elongation to break of about 400 to 1500%.        26. The glove of item 24 or 25, wherein the chlorobutadiene is        selected from the group consisting of 2-chloro-1,3-butadiene,        2,3-dichloro-1,3-butadiene and combinations thereof.        27. The glove of any one of items 24 to 26, wherein the        carboxylic acid or ester is an ethylenically unsaturated        carboxylic acid or ester having the formula:

CR¹H═CR²—C(O)—OR³

or

CR¹H═CR²—O—C(O)—R³

whereinR¹ is hydrogen, an alkyl radical containing 1 to 4 carbon atoms,—C(O)—OR⁴ or —R⁵—C(O)—OH, wherein R⁴ is hydrogen or an alkyl radicalcontaining 1 to 4 carbon atoms and R⁵ is an alkyl radical containing 1to 4 carbon atoms;R² is hydrogen, an alkyl radical containing 1 to 4 carbon atoms, or acarboxymethyl radical;R³ is hydrogen, an alkyl radical containing 1 to 4 carbon atoms, or—R⁶O—C(O)—CR⁷═CR⁸, wherein R⁶ is an alkyl radical containing 1 to 4carbon atoms, and R⁷ and R⁸ are each independently hydrogen or an alkylradical containing 1 to 4 carbon atoms; andcis or trans isomers thereof28. The glove of any one of items 24 to 27, wherein the carboxylic acidor ester is selected from the group consisting of acrylic acid,methacrylic acid, crotonic acid, fumaric acid, maleic acid, citraconicacid, glutaconic acid, vinyl acetate, methyl acrylate, methacrylateester, ethylenediol dimethacrylate, butanediol dimethacrylate,methymethacrylate, butylmethacrylate, glacialmethacrylic acid andcombinations thereof.29. The glove of any one of items 24 to 28, wherein the carboxylic acid-or ester-grafted polychlorobutadiene contains the carboxylic acid orester in an amount of from 0.01% to 8% by weight of the chlorobutadieneunits present in the polymer.30. The glove of any one of items 24 to 29, wherein the polymercomprises from 10 to 60% or 10 to 58% chlorine by weight of thechlorobutadiene units present in the polymer.31. The glove of any one of items 24 to 30, wherein the cross-linkingagent comprises an ionic cross-linking agent and a covalentcross-linking agent.32. The glove according to item 31, wherein the ionic cross-linkingagent is a metal oxide or metal hydroxide.33. The glove according to item 32, wherein the metal oxide or metalhydroxide is selected from one or a mixture of agents from the groupconsisting of lead oxide, magnesium oxide, barium oxide, zinc oxide,manganese oxide, copper oxide, nickel oxide, aluminium oxide, zinchydroxide, magnesium hydroxide, barium hydroxide, manganese hydroxide,copper hydroxide, aluminium hydroxide and nickel hydroxide.34. The glove according to item 31, wherein the covalent cross-linkingagent is sulphur or a sulphur-containing vulcanising agent.35. The glove of item 32 or 33, wherein the amount of metal-oxide ormetal hydroxide cross-linking agent in the composition is in the range1.0-10.0 phr, 2.0-8.0 phr, 2.5-10.0 phr, 5.0-10.0 phr, 3.0-7.0 phr,3.0-6.0 phr, 4.0-7.0 phr, 4.0-6.0 phr, 4.0-5.0 phr, 2.0-5.0 phr, 2.0-4.0phr, 3.0-4.0 phr36. The glove of item 34, wherein the amount of sulphur orsulphur-containing vulcanising agent is in the range 0.0-3.5 phr,0.01-3.5 phr, 0.01-3.0 phr, 0.01-2.0 phr, 0.01-1.5 phr, 0.01-1.0 phr or0.01-0.5 phr37. The glove of any one of items 24 to 36, wherein the elastomeric filmfurther comprises a second elastomer selected from the group consistingof nitrile rubber, styrene butadiene rubber, butyl rubber, polyisoprene,polychloroprene, polybutadiene, polyvinylchloride, polyurethane, styrenediblock copolymers, styrene triblock copolymers, acrylic polymers andmixtures thereof.38. The glove of item 37, wherein the second elastomer is carboxylated,non-carboxylated or a mixture of carboxylated and non-carboxylatedelastomers.39. The glove of item 37 or 38, wherein the second elastomer is presentin an amount of from 0% up to 95% by weight of the polymer component ofthe composition.40. The glove of any one of items 24 to 39, wherein the averagethickness of the elastomeric film is between about 0.01 mm to about 3mm.41. The glove of any one of items 24 to 40, wherein the glove comprisesfrom 1 to layers of elastomeric film composition, and each layer isproduced by a separate dipping step.42. A method of manufacturing an elastomeric film comprising the stepsof:

-   -   (i) dipping a former into a composition of any one of items 1 to        18 to produce a layer of elastomeric film-forming composition on        the former, and    -   (ii) drying and curing the elastomeric film-forming composition.        43. The method of item 42, further comprising, prior to step        (i), the steps of:    -   (a) dipping the former into a coagulant, followed by    -   (b) drying or partially drying the coagulant-dipped former.        44. A method of manufacturing an elastomeric film comprising the        steps of:    -   (i) dipping a former into a composition of any one of items 1 to        18 to produce a layer of elastomeric film-forming composition on        the former,    -   (ii) drying the elastomeric film-forming composition,    -   and    -   (v) drying and curing the layered elastomeric film.        45. A multiple-coating method of manufacturing a layered        elastomeric film comprising the steps of:    -   (i) dipping a former into a composition of any one of items 1 to        18 to produce a layer of elastomeric film-forming composition on        the former,    -   (ii) drying the elastomeric film-forming composition,    -   (iii) dipping the former into a composition of any one of items        1 to 18 to produce a further layer of elastomeric film-forming        composition on the former,    -   (iv) optionally repeating the drying step (ii) and the further        dipping step (iii), and    -   (v) drying and curing the layered elastomeric film.        46. The method of item 44 or 45, further comprising, prior to        step (i), the steps of:    -   (a) dipping the former into a coagulant, followed by    -   (b) drying or partially drying the coagulant-dipped former.        47. The method of any one of items 42 to 46, wherein the drying        step and the dipping step are repeated to produce a film having        from 2 to 15 layers.        48. The method of any one of items 42 to 47, wherein the film        has between 1-15, 2-6, 2-5, 1-4, 2-3, or 1-3 layers.        49. The method of any one of items 42 to 48, wherein the former        is a hand-shaped mould, and the layered elastomeric film is in        the shape of a glove.        50. The elastomeric film produced by the method of any one of        items 42 to 49.        51. Use of an elastomeric film-forming composition comprising:    -   a carboxylic acid- or ester-grafted polychlorobutadiene, and    -   one or more cross-linking agents,        in the manufacture of a glove.

1. An elastomeric film-forming composition comprising: (a) a polymercomponent comprising a carboxylic acid- or ester-graftedpolychlorobutadiene, and (b) one or more cross-linking agents, whereinthe carboxylic acid or ester-grafted polychlorobutadiene containscarboxylic acid or ester grafting in an amount of from 0.01% to 8% byweight of chlorobutadiene units present in the carboxylic acid orester-grafted polychlorobutadiene.
 2. The composition of claim 1,wherein the polychlorobutadiene is selected from the group consisting ofa polymer of 2-chloro-1,3-butadiene, a polymer of2,3-dichloro-1,3-butadiene and copolymers comprising2-chloro-1,3-butadiene and 2,3-dichloro-1,3-butadiene.
 3. Thecomposition of claim 1, wherein the carboxylic acid or ester-graftedpolychlorobutadiene comprises from 10 to 60% chlorine by weight of thechlorobutadiene units present in the carboxylic acid or ester-graftedpolychlorobutadiene.
 4. The composition of claim 1, wherein aconcentration of total solids in the composition is between 5-60% byweight of the composition.
 5. The composition of claim 1, wherein thecross-linking agent is selected from the group consisting of carbamates,thiocarbamates, thiurams, thiourea, thiazoles, guanidines,aldehyde/amine-based accelerators, ionic cross-linking agents, organicand inorganic metal oxides, organic and inorganic metal hydroxides,organic and inorganic peroxides, covalent cross-linking agents, sulphur,crosslinking monomers, reactive oligomers, polyisocyanate oligomers,functional crosslinkable polymers; derivatives of ethylene glycoldi(meth)acrylate, derivatives of methylenebisacrylamide,formaldehyde-free crosslinking agents, divinylbenzene, divinylether,diallyl phthalate, divinylsulfone and combinations thereof.
 6. Thecomposition of claim 5, wherein the cross-linking agent comprises anionic cross-linking agent and a covalent cross-linking agent.
 7. Thecomposition of claim 6, wherein the ionic cross-linking agent is a metaloxide or metal hydroxide.
 8. The composition of claim 6, wherein thecovalent cross-linking agent is at least one of (i) sulphur and (ii) asulphur-containing vulcanising agent.
 9. The composition according toclaim 1, wherein an amount of cross-linking agent in the composition isin the range of 0.5-15.0 phr.
 10. The composition of claim 1, whereinthe polymer component further comprises a second elastomer selected fromthe group consisting of nitrile rubber, styrene butadiene rubber, butylrubber, polyisoprene, polychloroprene, polybutadiene, polyvinylchloride,polyurethane, styrene diblock copolymers, styrene triblock copolymers,acrylic polymers and mixtures thereof.
 11. The composition of claim 10,wherein the second elastomer is carboxylated, non-carboxylated or amixture of carboxylated and non-carboxylated elastomers.
 12. Thecomposition of claim 10, wherein the second elastomer is present in anamount of 0-95% by weight of the polymer component of the composition.13. The composition of claim 1, wherein the carboxylic acid orester-grafted polychlorobutadiene contains carboxylic acid or estergrafting in an amount of from about 0.5% to about 5% by weight of thechlorobutadiene units present in the carboxylic acid or ester-graftedpolychlorobutadiene.
 14. A dipped article made from an elastomericfilm-forming composition comprising: (a) a carboxylic acid- orester-grafted polychlorobutadiene, and (b) one or more cross-linkingagents, wherein the carboxylic acid or ester-grafted polychlorobutadienecontains carboxylic acid or ester grafting in an amount of from 0.01% to8% by weight of chlorobutadiene units present in the carboxylic acid orester-grafted polychlorobutadiene.
 15. The dipped article of claim 14,wherein the article is a glove.
 16. The dipped article of claim 14,wherein an average thickness of the elastomeric film is between about0.01 mm to about 3 mm.
 17. The dipped article of claim 14, wherein anaverage thickness of the elastomeric film is between about 0.01 mm toabout 5 mm.
 18. The dipped article of claim 14, wherein the elastomericfilm comprises from 1 to 15 layers, and each layer is produced by aseparate dipping step.
 19. The dipped article of claim 14, wherein thedipped article has at least one of (i) a tensile strength of greaterthan or equal to about 2000 psi, (ii) a modulus at 300% of about 100 to2000 psi, (iii) a stress at 500% of about 200 to 3000 psi, and (iv) anelongation to break of about 400 to 1500%.
 20. A method of manufacturingan elastomeric film comprising the steps of: dipping a former into anelastomeric film-forming composition comprising (a) a carboxylic acid-or ester-grafted polychlorobutadiene, and (b) one or more cross-linkingagents, to produce a layer of elastomeric film-forming composition onthe former, wherein the carboxylic acid or ester-graftedpolychlorobutadiene contains carboylic acid or ester grafting in anamount of 0.1% to 8% by weight of chlorobutadiene units present in thecarboxylic acid or ester-grafted polychlorobutadiene, and (ii) dryingand curing the elastomeric film-forming composition.
 21. The method ofclaim 20 wherein, prior to step (i), the method comprises the steps of:dipping the former into a coagulant, followed by drying or partiallydrying the coagulant-dipped former.
 22. The method of claim 20, wherein,following step (ii), the method comprises the steps of: (iii) dippingthe former into a second elastomeric film-forming composition comprising(a) a carboxylic acid- or ester-grafted polychlorobutadiene, and (b) oneor more cross-linking agents, to produce a further layer of elastomericfilm-forming composition on the former, and (v) drying and curing thelayered elastomeric film.
 23. The method of claim 20, wherein the dryingstep and the dipping step are repeated to produce a film having from 2to 15 layers.
 24. The method of claim 20, wherein the former is ahand-shaped mould, and the layered elastomeric film is in the shape of aglove.
 25. The elastomeric film produced by the method of claim
 20. 26.A method of manufacturing a glove, comprising the use of an elastomericfilm-forming composition comprising: (a) a carboxylic acid- orester-grafted polychlorobutadiene, wherein the carboxylic acid orester-grafted polychlorobutadiene contains carboxylic acid or estergrafting in an amount of from 0.01% to 8% by weight of thechlorobutadiene units present in the polymer, and (b) one or morecross-linking agents.